Merge pull request #34261 from matildasmeds/guides_remove_upgrade_section_from_asset_pipeline_guide

Remove "Upgrading from Old Versions" from Asset Pipeline Guide [skip ci]

guides/source/asset_pipeline.md

@@ -1234,60 +1234,3 @@ it as a preprocessor for your mime type.
 Sprockets.register_preprocessor 'text/css', AddComment
 ```
 
-Upgrading from Old Versions of Rails
-------------------------------------
-
-There are a few issues when upgrading from Rails 3.0 or Rails 2.x. The first is
-moving the files from `public/` to the new locations. See [Asset
-Organization](#asset-organization) above for guidance on the correct locations
-for different file types.
-
-Next is updating the various environment files with the correct default
-options.
-
-In `application.rb`:
-
-```ruby
-# Version of your assets, change this if you want to expire all your assets
-config.assets.version = '1.0'
-
-# Change the path that assets are served from config.assets.prefix = "/assets"
-```
-
-In `development.rb`:
-
-```ruby
-# Expands the lines which load the assets
-config.assets.debug = true
-```
-
-And in `production.rb`:
-
-```ruby
-# Choose the compressors to use (if any)
-config.assets.js_compressor = :uglifier
-# config.assets.css_compressor = :yui
-
-# Don't fallback to assets pipeline if a precompiled asset is missed
-config.assets.compile = false
-
-# Generate digests for assets URLs.
-config.assets.digest = true
-
-# Precompile additional assets (application.js, application.css, and all
-# non-JS/CSS are already added)
-# config.assets.precompile += %w( admin.js admin.css )
-```
-
-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`.
-
-The following should also be added to your `Gemfile`:
-
-```ruby
-gem 'sass-rails',   "~> 3.2.3"
-gem 'coffee-rails', "~> 3.2.1"
-gem 'uglifier'
-```