The return types for `webbrowser`'s API aren't documented

[akx]

Documentation

Related to https://stackoverflow.com/a/78930912/51685, it isn't clear that webbrowser.open() and friends return booleans.

(I have a PR fired up for this.)

Linked PRs

• gh-123494: Improve documentation for webbrowser return types #123495
• [3.13] gh-123494: Improve documentation for webbrowser return types (GH-123495) #123548
• [3.12] gh-123494: Improve documentation for webbrowser return types (GH-123495) #123549

[hugovk]

Merged and backported.