Document 'attr' parameter for window.vline() in curses module

[slateny]

Documentation

Function window.vline is missing the attr parameter, which defaults to A_NORMAL (this is already documented).

Linked PRs

• gh-100616: Document 'attr' parameter for window.vline() in curses module #24961
• [3.11] gh-100616: Document 'attr' parameter for window.vline() in curses module (GH-24961) #100625
• [3.10] gh-100616: Document 'attr' parameter for window.vline() in curses module (GH-24961) #100626