Link the "Installing from archive" wiki page more prominently

[cer28]

After getting a mostly working configuration through reverse engineering and trial and error, by accident I discovered the Installing from archive wiki page, which was the holy grail I needed from the beginning. It's not linked from the Installation section of the README. In the repository, I only see it listed as one item in the middle of the wiki list of all pages, and in the 1.1.1 tag notes. On the wider internet, it's mentioned from the 2018 training tutorial, and in answer to a number of user list questions on where the setup instructions are.

I had been looking for instructions all through the process, but didn't get lucky with the search terms until the nth try. I thought it was odd that instructions were missing, but assumed it was related to moving the 2.x archive to Shibboleth hosting.