[latexrefman] Add acknowledgement

[Hefferon, Jim S.]

Added acknowledgement for latex2e-reference.

I adjusted the wording in Lengths.  It is awkward that to show a box (basically by outlining
it with \fbox) you either allow the border to add extra length, or else you get lots of overfull stuff.  (maybe colors would be better?)

I did not do the preparation for splitting into lots of little HTML files.  Another day.

Jim

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