Document assert_queries and assert_no_queries [ci-skip]

[siaw23]

Motivation / Background

This Pull Request has been created because #50281 is missing some documentation.

Detail

This Pull Request documents assert_queries and assert_no_queries

Additional information

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[fatkodima]

Maybe move these closer to the Active Record related assertions? The last ones are related to the controllers.

[fatkodima]

Nevermind, the mentioned ones are not actually active record related.