[ci skip] Fix broken url in plugins guide
Merge pull request #16472 from y-yagi/patch-1

[ci skip] Fix broken url in plugins guide
users_dont_suck_but_only_we_suck_and_only_our_tests_are_order_dependent!

Calling ActiveSupport::TestCase.i_suck_and_my_tests_are_order_dependent! in AS::TestCase makes
everyone's tests order dependent, which should never be done by the framework.
Remove old setup from AS test case

This was added back in Rails 3 on
c4a6109286909c394e8c5bfc471a1eb9de245d2b, and is not being used anymore.
CHANGELOG entry for TestCase.i_suck_and_my_tests_are_order_dependent! fix
use 'based on' instead of 'based off' [ci skip]
Nobody sucks so nobody should call this awful method name
Merge pull request #16476 from akshay-vishnoi/doc-changes

[ci skip] use "based on" or "based off of"
:bomb:
Enable Cache-Control headers on assets by default

When using assets generated by the asset pipeline we can rely on digest filenames to serve them with a Cache-Control header with little to no problem. This PR sets that value by default to 3600 seconds (1 hour). This is the duration that the CDN will serve this file before needing to hit the Rails server (if it is set as an origin server). It is also the duration that the browser will retain the file in cache.

Ideally we want to set this to the maximum value possible `2592000` but this value affects __all__ assets not just digest assets. It is up to the developer to optimize this value beyond the default.