[docs] [issue21063] Touch up one-line descriptions of modules for module index

Change by Sanchit Khurana <sanchitkhuranask@gmail.com>: ---------- pull_requests: +16848 stage: needs patch -> patch review pull_request: https://github.com/python/cpython/pull/17363 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue21063> _______________________________________