Standardize capitalization of scenarios.

When viewing in Relish, scenarios read as section titles. General
punctuation dictates that section titles should start capitalized.
Use a more explicit scenario description.
Update feature description.
Standardize on `RSpec.describe` over `describe`.
Surround inline code in back ticks.
Correct note about x-aliases now skipping.
Make CLI flags explicit across features.
Adjust grammar and HTML rendering.

- Explicitly specify the code block format for Relish
- Adjust wording to keep related topics together
Add `skip` to CLI output --format scenarios.
Add new scenario describing a simple name alias.

Adjust the spec file names to match the description.
Whitespace only update.
Replace order feature with basic description.
Use code backticks in feature and scenario names.
Use triple backticks for description code blocks.

Relish supports using triple backticks for code blocks in markdown. This
is primarily used in feature descriptions. Relish has a few issues with
supporting naming the syntax with triple backticks. We'll standardize on
this method while Relish works the remaining issues out.
Minor grammatical update.

- Bold notes, warnings, etc. titles
- Move convention into a sub-heading
Standardize on `RSpec.describe` over `describe`.
Update allowed syntax to remove should by default.

- Remove one-liner `should` and `should_not`
- Allow for full override of the customizations
Include new doc standards with new feature.

Adjust whitespace for feature description based on space taken by added
tags.
A few more minor grammar and formatting updates.
Merge pull request #1461 from rspec/misc-doc-updates

Misc doc updates