Document `RotatingFileHandler.shouldRollover()` and `TimedRotatingFileHandler.shouldRollover()`

[AllenSH12]

Documentation

The RotatingFileHandler and TimedRotatingFileHandler do not document the shouldRollover method that they both implement.

Linked PRs

• (gh-134817) Documents [Timed]RotatingFileHandler shouldRollover method #134818
• [3.14] gh-134817: Document [Timed]RotatingFileHandler shouldRollover method (GH-134818) #134823
• [3.13] gh-134817: Document [Timed]RotatingFileHandler shouldRollover method (GH-134818) #134824