Generate and include man pages from .rst sources

[ximon18]

Using sphinx.

This is something we currently do manually and are doing in more and more projects.

Manual steps are brittle in that they are not necessarily documented or the documentation becomes outdated, an automated process is both self-documenting and has to be kept up-to-date in order to work, and fixes in Ploutos benefit all projects using it at once instead of fixing the process in each project.

Also, having the right versions of the right Python packages installed is an extra burden on the releasing user if they have no edited/generated docs before.