Adding markdown documents in in app documentation

[dirkpetersen]

Currently we are using default Jinja2 rendered HTML for the documentation page in side flask apps

https://github.com/FredHutch/postgres_container_mgmt/blob/master/postgresdb/templates/documentation.html

This should really be written in markdown and rendered accordingly, perhaps with something like https://pypi.python.org/pypi/flask_markdown2