Expand INSTALL.md to a more complete operator's guide
In the last week or two we spent some time on writing more complete operator's guides for the various metrics services. This is for our October milestone: "Provide user-friendly documentation that empowers users to independently operate CollecTor instances."
I'll attach the latest operator's guide for CollecTor in a minute. The funny whitespace comes from the document being a LaTeX table with commented-out columns for the other metrics services.
I'd like to put the text from that PDF into the current INSTALL.md, maybe after reformatting some things in Markdown.
I'd also like to remove the current README.md, because there should be just one document telling operators how to use CollecTor, and we can probably expect most operators to know how to use gpg.
Thoughts?