Fix typo in nodoc should be `:nodoc:` for RDoc to parse correctly
[ci skip] Fix HTML format on comment
Merge pull request #18081 from yui-knk/fix/capture_helper

[ci skip] Fix HTML format on comment
Add docs for AS::TestCase::test_order

Document `test_order` and `test_order=` from `ActiveSupport::TestCase`.

[ci skip]