[tex-live] map file / new path settings

[Karl Berry]

    the TeX Live documentation for the next release should have precise
    instructions for people who want to adopt their local tree to the
    new release.

I added your text (thanks for writing) to
http://tug.org/texlive/bugs.html.  Could you please check it over?
Then I'll add it to the documentation for the next release.

Barbara also asked me to write up a short note for TUGboat about it, so
I'll do that.

Thanks.