Updating library/bundle installation docs to use the new composer require (no version) functionality
Fixing bad link
Correct a typo.

Removed uncorrect "load use" phrase part, and replaced it with "you can
use", which I guess conveys the original meaning of the phrase better.
first import of the "Official Best Practices" book
Fixed some technical problems as suggested by Wouter
Added an index directive to the first chapter
updated fabpot/sphinx-php module reference
added the missing "best-practice" directive import in Sphinx configuration
minor #4325 [Components][Form] Correct a typo (fabschurt)

This PR was merged into the 2.3 branch.

Discussion
----------

[Components][Form] Correct a typo

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | n/a

Removed uncorrect "load use" phrase part, and replaced it with "you can
use", which I guess conveys the original meaning of the phrase better.

Commits
-------

3d3388d Correct a typo.
Renamed "official best practices" to "best practices"
Fixed some typos reported by @henrikbjorn
Improve cookbook entry for error pages in 2.3~
feature #4294 Improve cookbook entry for error pages in 2.3~ (mpdude)

This PR was merged into the 2.3 branch.

Discussion
----------

Improve cookbook entry for error pages in 2.3~

This PR cherry-picks the improvements from #4293 that apply to 2.3 as well (almost all!).

It also addresses some of the considerations in #4181.

Commits
-------

f74b6f2 Improve cookbook entry for error pages in 2.3~
[#4290] Re-adding version back
Re-adding one more version
feature #4290 Updating library/bundle install docs to use "require" (weaverryan)

This PR was merged into the 2.3 branch.

Discussion
----------

Updating library/bundle install docs to use "require"

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | -

As of composer/composer#3906, you can now simply install a library via:

```
php composer.phar require myname/my-lib
```

The latest version if chosen for you. I've replaced all mentions of modifying composer.json and running `composer update` with using the `require` command. I think the result is much simpler :).

Thanks!

Commits
-------

d7ccbf3 Re-adding one more version
ab2a688 [#4290] Re-adding version back
a174a2b Fixing bad link
1a7c4b9 Updating library/bundle installation docs to use the new composer require (no version) functionality
Update http_cache.rst

Explained how the parameters are passed to the controller - named parameters
Clarifying a bit more that you're passing variables into your controller
Putting #pull-request-format anchor link back, which we link to in our contrib notes
Added config example for Varnish 4.0