Even if this is not exactly the same, let's add a new-line character
instead of two spaces. While it's specified in the Markdown specs that
adding spaces at the end of the line creates a break-line tag, this is
a brittle approach as people may remove them saving the file on certain
editors.

[ci skip]

not 2 caveats with one of them being 2 config changes [ci skip]

to match arguments used in sprockets-rails [ci skip]

Follow up to #15636.

/cc @hundredwatt

Directives need to be placed on their own lines in order to work. Tested on: `Server version: Apache/2.2.22 (Ubuntu); Server built:   Mar 19 2014 21:11:15`

in Asset Pipeline guide.

[skip ci]

[ci skip]

Updated CHANGELOG.md with entry about :host in asset_url

The name of the gem is `uglifier` and all other references
use `uglifier`, not `uglify`.

[ci skip]

sprockets-rails 2.1 needs the precompile list to be available in all
environments.

Explain how form_for :article is able to pull in the properties of @article
Make it clear that article_id is generated due to the association set up

Add link to the rails function that uses X-Sendfile.
Add links to apache and nginx docs for the header

By default `config.assets.raise_runtime_errors` should be set to `true` in development for new apps.

Source: https://github.com/rails/sprockets-rails/pull/100

[ci skip]

- Right now the comment was not rendering properly.
  # The Expires* directives requires the Apache module
  `mod_expires` to be
  # enabled.
- After this change -
  # The Expires* directives requires the Apache module
  # `mod_expires` to be enabled.

by default included to precompile only non-js/css files from `app/assets` and `application.(css|js)`