Incorrect hook docs for `wp_save_post_revision_check_for_changes`

[johnbillion]

The hook docs for the $last_revision and $post parameters in the wp_save_post_revision_check_for_changes filter are incorrect.

[DrewAPicture]

In 30119:

Correct two parameter types in the wp_save_post_revision_check_for_changes hook documentation.

Props johnbillion.
Fixes #30185.