Redirect pages back to main site, change templates

[davetcc]

As discussed elsewhere here and on TcMenu discussions, I am moving the hosting back to the main site. You can still raise PRs against this documentation and they will be hosted on the main site.

Why?

• New users have to go through three different sites with the documentation feeling disjointed.
• I'm having to look after two separate sites, and it's mainly me editing and maintaining it.
• The Hugo template is really out of date, fixing it would be a large job.
• There are no admin utilities for Github pages.

[davetcc]

Although the work around this is complete, I'll leave it open for a while for understanding.