[request for review] Port of s6 documentation to mdoc(7)

[Alexis <flexibeast@gmail.com>]

Hi all,

i recently started using 66 instead of runit on Void - thanks to 
@Obarun, @mobinmob and @teldra for their work and help!

Consequently, and further to 
https://www.mail-archive.com/supervision@list.skarnet.org/msg02278.html 
:

> if people like man pages, they should have man pages, so it's 
> been a
> few years that I have appealed to the community for this ... I 
> want
> s6 to be accessible, but I figure that if people really wanted 
> man
> pages, they'd write man pages

i've spent the last couple of weeks porting the s6 documentation 
to mdoc(7) format:

  https://github.com/flexibeast/s6-man-pages

since i really want man pages, and much prefer them to HTML for 
system-level software. :-)

i don't consider the current state of the repo to be 'ready' in a 
general sense, but i do feel it's mostly done, and certainly 
amenable to review. i think this might be a good time to give 
myself a short break from working on it, so i can then come back 
and do a review pass with fresher eyes.

The porting has been done manually, with no automation involved; 
this has allowed me to use semantic markup as much as possible, 
which of course also facilitates searching for content with 
`apropos(1)`.

Several things to note:

* i've changed page layouts to fit mdoc(7) conventions.

* During the porting process, i developed ideas about what might 
  be the best way to do things, so documentation ported earlier 
  might not follow the same style as the documentation ported more 
  recently. This is something i hope to check in my review pass.

* There are currently no cross-references to the execline suite or 
  skalibs. However, i'm willing to port that documentation as 
  well, together with the s6-rc documentation.

* Inline links to things such as djb's software are not yet 
  included. The `Lk` macro allows one to supply link text as well 
  as the URL, but the resulting output would require changes to 
  the text to make it read satisfactorily. Regardless, i can add 
  the relevant links in "SEE ALSO" sections.

* i've corrected a number of typos and grammatical issues, and 
  discovered what i believe might be couple of errors:

  * s6-softlimit: The "Options" section refers to "-r allmem" 
  rather than "-r res".

  * s6-ftrig-listen: The "Options" section says: "By default, 
  s6-ftrig-listen1 waits indefinitely for a matching series of 
  events." Given the context, i presume this should be 
  "s6-ftrig-listen"?

That said, although i've tried to be careful, i might have 
introduced new errors, or made mistakes in my choice of macros, so 
proofreading would be appreciated. :-)


Alexis.