This fixes up a handful of relatively small issues with the manual:

Perforce moved the documentation for stunnel to a new article.
We weren't including the server monitoring doc in the toctrees.
Said monitoring doc had a broken link to the docker install docs.
Django has removed the request-middleware and response-middleware

  refs from their docs, so I reworded it to not try to link to them.
We weren't linking to the correct django-evolution doc location.
The diff commit validation resource was giving the wrong name for the

  relevant doc ref.

Built docs and checked links.