Document the curses module variables LINES and COLS

[serhiy-storchaka]

In the curses.update_lines_cols() description LINES and COLS are referred as the environment variables. But actually they are the curses module variables.

Linked PRs

• gh-107008: Document the curses module variables LINES and COLS #107011
• [3.12] gh-107008: Document the curses module variables LINES and COLS (GH-107011) #107057
• [3.11] gh-107008: Document the curses module variables LINES and COLS (GH-107011) #107058