* divide text into subsections according to function
* group I/O, math functions together (similarily to how gawk manpage
is structured) and provide easily parsable
list, so that it's much easier to find information about individual
functions
* sort function and variable list by alphabet
to dist/nawk/, since it's not likely mdoc formatted manpage would become
part of nawk distrubution.
Hopefully mdoc macros are used mostly correctly here.