Repository: ember-cli/ember-cli (js)

Issue:
Improve the Addon README.md Blueprint
Hi all,

Looking at the recent changes to better improve the overall workflows of new applications (ember-welcome-page) as well as improving the debugging via the newly themed debug page, I think we should re-visit how addons are presented to rest of the community. 

Today, there are thousands of addons, each solving a different use case. These are the couple of things i've noticed:

1. The README is not detailed enough or missing key information
2. The README is not structured in an easy to read / understandable way.
3. Across each addon, every README is completely different.

My proposal - A well structured README blueprint for newly created addons to follow. 

It can go something like this:

```md
#  My Addon Name

## Overview
This section details what this addon is and what sort of problems it solves

## Features
This section shows the core features of this addon: 

i.e.)
- Feature 1
- Feature 2
- Feature 3

## Installation
\```
ember install my-addon-name
\``` 

## Usage
This section details how you actually use this addon.

## Contributing
This section details how to contribute to this addon.
```

The above template is a WIP and I'd love some feedback!

Not only can this standardize the addon community even more, but it can very well better the documentation being written (as it will be more structured) and improve the experience of new ember users / new addon developers. 

Pull request description:
Improve default addon README
This PR changes the `README.md` that is generated by default for new addons in a few ways:

- Adds an automatically generated "Installation" section
- Adds an empty "Usage" section
- Moves the current contents into a "Contributing" section
- Adds a "License" section
- Uses [Setext headings](http://spec.commonmark.org/0.28/#setext-heading) to better emphasize the README sections in raw text mode

This is roughly similar to what we've been doing in some of our own addons already, e.g. https://github.com/ember-cli/ember-cli-eslint/blob/master/README.md

Resolves #7278

/cc @offirgolan

Patch:
diff --git a/blueprints/addon/files/README.md b/blueprints/addon/files/README.md
index bed39d157..292815c90 100644
--- a/blueprints/addon/files/README.md
+++ b/blueprints/addon/files/README.md
@@ -1,26 +1,46 @@
-# <%= addonName %>
+<%= addonName %>
+==============================================================================
 
-This README outlines the details of collaborating on this Ember addon.
+[Short description of the addon.]
 
-## Installation
+Installation
+------------------------------------------------------------------------------
 
-* `git clone <repository-url>` this repository
+```
+ember install <%= addonName %>
+```
+
+
+Usage
+------------------------------------------------------------------------------
+
+[Longer description of how to use the addon in apps.]
+
+
+Contributing
+------------------------------------------------------------------------------
+
+### Installation
+
+* `git clone <repository-url>`
 * `cd <%= addonName %>`
 * `<% if (yarn) { %>yarn<% } else { %>npm<% } %> install`
 
-## Running
+### Running tests
 
-* `ember serve`
-* Visit your app at [http://localhost:4200](http://localhost:4200).
+* `ember test` – Runs the test suite on the current Ember version
+* `ember test --server` – Runs the test suite in "watch mode"
+* `<% if (yarn) { %>yarn<% } else { %>npm<% } %> test` – Runs `ember try:each` to test your addon against multiple Ember versions
+
+### Running the dummy application
 
-## Running Tests
+* `ember serve`
+* Visit the dummy application at [http://localhost:4200](http://localhost:4200).
 
-* `<% if (yarn) { %>yarn<% } else { %>npm<% } %> test` (Runs `ember try:each` to test your addon against multiple Ember versions)
-* `ember test`
-* `ember test --server`
+For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
 
-## Building
 
-* `ember build`
+License
+------------------------------------------------------------------------------
 
-For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
+This project is licensed under the [MIT License](LICENSE.md).


Test patch:
diff --git a/tests/fixtures/addon/npm/README.md b/tests/fixtures/addon/npm/README.md
index b8e8e3d9a..744417746 100644
--- a/tests/fixtures/addon/npm/README.md
+++ b/tests/fixtures/addon/npm/README.md
@@ -1,26 +1,46 @@
-# foo
+foo
+==============================================================================
 
-This README outlines the details of collaborating on this Ember addon.
+[Short description of the addon.]
 
-## Installation
+Installation
+------------------------------------------------------------------------------
 
-* `git clone <repository-url>` this repository
+```
+ember install foo
+```
+
+
+Usage
+------------------------------------------------------------------------------
+
+[Longer description of how to use the addon in apps.]
+
+
+Contributing
+------------------------------------------------------------------------------
+
+### Installation
+
+* `git clone <repository-url>`
 * `cd foo`
 * `npm install`
 
-## Running
+### Running tests
 
-* `ember serve`
-* Visit your app at [http://localhost:4200](http://localhost:4200).
+* `ember test` – Runs the test suite on the current Ember version
+* `ember test --server` – Runs the test suite in "watch mode"
+* `npm test` – Runs `ember try:each` to test your addon against multiple Ember versions
+
+### Running the dummy application
 
-## Running Tests
+* `ember serve`
+* Visit the dummy application at [http://localhost:4200](http://localhost:4200).
 
-* `npm test` (Runs `ember try:each` to test your addon against multiple Ember versions)
-* `ember test`
-* `ember test --server`
+For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
 
-## Building
 
-* `ember build`
+License
+------------------------------------------------------------------------------
 
-For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
+This project is licensed under the [MIT License](LICENSE.md).
diff --git a/tests/fixtures/addon/yarn/README.md b/tests/fixtures/addon/yarn/README.md
index 3dc559c2f..df6379b26 100644
--- a/tests/fixtures/addon/yarn/README.md
+++ b/tests/fixtures/addon/yarn/README.md
@@ -1,26 +1,46 @@
-# foo
+foo
+==============================================================================
 
-This README outlines the details of collaborating on this Ember addon.
+[Short description of the addon.]
 
-## Installation
+Installation
+------------------------------------------------------------------------------
 
-* `git clone <repository-url>` this repository
+```
+ember install foo
+```
+
+
+Usage
+------------------------------------------------------------------------------
+
+[Longer description of how to use the addon in apps.]
+
+
+Contributing
+------------------------------------------------------------------------------
+
+### Installation
+
+* `git clone <repository-url>`
 * `cd foo`
 * `yarn install`
 
-## Running
+### Running tests
 
-* `ember serve`
-* Visit your app at [http://localhost:4200](http://localhost:4200).
+* `ember test` – Runs the test suite on the current Ember version
+* `ember test --server` – Runs the test suite in "watch mode"
+* `yarn test` – Runs `ember try:each` to test your addon against multiple Ember versions
+
+### Running the dummy application
 
-## Running Tests
+* `ember serve`
+* Visit the dummy application at [http://localhost:4200](http://localhost:4200).
 
-* `yarn test` (Runs `ember try:each` to test your addon against multiple Ember versions)
-* `ember test`
-* `ember test --server`
+For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
 
-## Building
 
-* `ember build`
+License
+------------------------------------------------------------------------------
 
-For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
+This project is licensed under the [MIT License](LICENSE.md).