Requesting PR review for small PR that adds a test

I have a short PR open that adds a test and updates some documentation. I would appreciate a few reviews/feedback.

PR Summary:

Add a test for the case when includes is used with a conditional hash. The test confirms that only associations that pass the conditional are eager loaded. Documentation for the includes method was updated to indicate that includes only loads associations that pass the provided conditional. Updating the docs and adding a test was prompted by #42743. There was some discussion on the expected behaviour includes when used with a conditional where clause.