[docs] [issue22014] Add summary table for OS exception <-> errno mapping

Nick Coghlan added the comment: Another idea would be to include fragments of the ASCII art hierarchy throughout the doc, but that's trickier than it sounds, since we just use literalinclude to generate the current one. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue22014> _______________________________________