gh-129873: IDLE: Improve help.py's method of parsing HTML (#129859)

In `help.copy_strip`, only copy the text `<section>`.  In `help.HelpParser.handle_starttag` and elsewhere, remove code to skip the no longer present html.  Add a reminder at the top of idle.rst to run copy_strip after changes.
---------

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Author: StanFromIreland

Doc/library/idle.rst

@@ -12,6 +12,9 @@ IDLE --- Python editor and shell
    single: Python Editor
    single: Integrated Development Environment
 
+..
+   Remember to update Lib/idlelib/help.html with idlelib.help.copy_source() when modifying this file.
+
 --------------
 
 IDLE is Python's Integrated Development and Learning Environment.

Lib/idlelib/News3.txt

@@ -19,6 +19,9 @@ Released on 2024-10-07
 
 gh-120104: Fix padding in config and search dialog windows in IDLE.
 
+gh-129873: Simplify displaying the IDLE doc by only copying the text
+section of idle.html to idlelib/help.html. Patch by Stan Ulbrych.
+
 gh-120083: Add explicit black IDLE Hovertip foreground color needed for
 recent macOS. Fixes Sonoma showing unreadable white on pale yellow.
 Patch by John Riggles.