[docs] [issue18779] Misleading documentations and comments in regular expression about alphanumerics and underscore

[Serhiy Storchaka]

Changes by Serhiy Storchaka <storchaka at gmail.com>:


----------
components: +Regular Expressions
nosy: +ezio.melotti, mrabarnett, pitrou
stage:  -> patch review

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue18779>
_______________________________________