gh-139707: Copy-strip change to idle.rst into idlelib (#143718)

On Windows, running `python -c "from idlelib.help import copy_strip;
copy_strip()"` after idle.html is built results in
`f:\dev\3x\Doc\build\html\library\idle.html
copied to f:\dev\3x\Lib\idlelib\help.html`
This PR commits the html change to idlelib/help.html.