GitLab

Vastly rewritten, and Solderpunk did not see any problems with it.

* added links to the IETF specifications being referenced.
* removed the text/gemini section (section 5) as that will be its own
  document.

I've reflowed the documents to make it easier for me to edit, and to make
diffs easier to read as I make changes to these documents.  Once everything
is finalized, they'll be reformatted back to a more Gemini friendly version,
so don't worry.