[texdoc] texdoc and regexes

[Karl Berry]

    I'm not quite sure I know what "normal regexes" mean

Basically, grep and egrep (er, grep -E).  There are POSIX standards
about regexps too, BTW.  (Which have their own problems, but anyway.)

    I wonder if it would not be more useful to do some
    shell-style globs instead. Wdyt?

Globs would be fine too.  Definitely much better than Lua regexps,
possibly better than normal regexps.  If there's already Lua support for
them, by all means, let's switch.

Thanks,
karl