Add information about IDLE to online contents

[StanFromIreland]

Clicking Complete table of contents on docs.python.org shows, in part,

A short line like:

Python's Integrated Development Environment

Maybe the remainder can be omitted?

@terryjreedy

Linked PRs

• gh-129699: Add description to IDLE doc title #129727
• [3.13] gh-129699: Add description to IDLE doc title (GH-129727) #129864
• [3.12] gh-129699: Add description to IDLE doc title (GH-129727) #129865

[terryjreedy]

This master html content index file is generated from the individual files when the doc set is created by Sphinx. The entries are derived from the header lines. Omitting other markup, tkinter.rst begins with "tkinter --- Python interface to Tcl/Tk", the same as above with --- converted to the continuous line. I suggest we add --- Python editor and shell to the title of Doc/library/idle.rst. Near the bottom of the file, we could expand the subsubsection 'idlelib' to idlelib --- implementation of IDLE application. Either suggest other additions to add or go ahead with a PR if you want.

For the module index py-modindex.html, accessed by clicking the top right button on the online pages, the extra explanation is the module synopsis. tkinter.rst has :synopsis: Interface to Tcl/Tk for graphical user interfaces. This seems only to be applicable to modules. Since IDLE is not a module, 'IDLE' does not belong there, which is why I added the idlelib section, with a synopsis.