Asset pipeline: Remove documentation about outdated `config.assets.compress` option

[ci skip]

guides/source/asset_pipeline.md

@@ -435,11 +435,11 @@ Sprockets uses manifest files to determine which assets to include and serve.
 These manifest files contain _directives_ - instructions that tell Sprockets
 which files to require in order to build a single CSS or JavaScript file. With
 these directives, Sprockets loads the files specified, processes them if
-necessary, concatenates them into one single file and then compresses them (if
-`Rails.application.config.assets.compress` is true). By serving one file rather
-than many, the load time of pages can be greatly reduced because the browser
-makes fewer requests. Compression also reduces file size, enabling the
-browser to download them faster.
+necessary, concatenates them into one single file and then compresses them
+(based on value of `Rails.application.config.assets.js_compressor`). By serving
+one file rather than many, the load time of pages can be greatly reduced because
+the browser makes fewer requests. Compression also reduces file size, enabling
+the browser to download them faster.
 
 
 For example, a new Rails application includes a default
@@ -1105,11 +1105,6 @@ NOTE: You will need an [ExecJS](https://github.com/rails/execjs#readme)
 supported runtime in order to use `uglifier`. If you are using Mac OS X or
 Windows you have a JavaScript runtime installed in your operating system.
 
-NOTE: The `config.assets.compress` initialization option is no longer used in
-Rails to enable either CSS or JavaScript compression. Setting it will have no
-effect on the application. Instead, setting `config.assets.css_compressor` and
-`config.assets.js_compressor` will control compression of CSS and JavaScript
-assets.
 
 ### Using Your Own Compressor
 
@@ -1290,8 +1285,8 @@ config.assets.digest = true
 
 Rails 4 and above no longer set default config values for Sprockets in `test.rb`, so
 `test.rb` now requires Sprockets configuration. The old defaults in the test
-environment are: `config.assets.compile = true`, `config.assets.compress = false`,
-`config.assets.debug = false` and `config.assets.digest = false`.
+environment are: `config.assets.compile = true`, `config.assets.debug = false` and
+`config.assets.digest = false`.
 
 The following should also be added to your `Gemfile`:
 

guides/source/configuring.md

@@ -157,8 +157,6 @@ pipeline is enabled. It is set to true by default.
 
 * `config.assets.raise_runtime_errors` Set this flag to `true` to enable additional runtime error checking. Recommended in `config/environments/development.rb` to minimize unexpected behavior when deploying to `production`.
 
-* `config.assets.compress` a flag that enables the compression of compiled assets. It is explicitly set to true in `config/environments/production.rb`.
-
 * `config.assets.css_compressor` defines the CSS compressor to use. It is set by default by `sass-rails`. The unique alternative value at the moment is `:yui`, which uses the `yui-compressor` gem.
 
 * `config.assets.js_compressor` defines the JavaScript compressor to use. Possible values are `:closure`, `:uglifier` and `:yui` which require the use of the `closure-compiler`, `uglifier` or `yui-compressor` gems respectively.