Add support for shell documentation

[osterman]

what

• Add support for man pages from markdown

why

• Geodesic has insufficient documentation in part because we haven't had a good way to deliver it
• Unix has solved this: man pages have been there forever. The problem is that man (groff) is no fun to write. Using pandoc we can convert markdown to valid man pages to make it easy to contribute documentation

references

• http://rtomayko.github.io/ronn/ronn-format.7.html (did not want to install ruby just to compile docs; using pandoc instead)
• https://pandoc.org/MANUAL.html
• https://en.wikipedia.org/wiki/Man_page
• https://babbage.cs.qc.cuny.edu/courses/cs701/Handouts/man_pages.html

[aknysh]

nitpick

[Nuru]

You should not have an empty geodesic_apkindex.md5. Do you maybe have *.md5 in your global .gitignore?

[osterman]

I ran the update command but didn’t pay attention to the result. Will check what’s wrong next time.