[latexrefman] Add mirroring.html

[Hefferon, Jim S.]

I added a file giving brief directions on mirroring.  (Full disclosure: it has CSS for "LaTeX".)  I was hoping it could be linked-to from the home page.

I added horizontal rules to the bottom of the html files in the split.  Sorry for the noise of all those files changing but I think it seemed to me that it makes more sense out of the link at the page bottom.

Jim

----------
https://en.wikipedia.org/wiki/Cluster_B_personality_disorders