There's no need to talk about update-alternatives here.

Our "make install" process does nothing with 'alternatives'.  Our RPMs do use
alternatives but they do the necessary update-alternatives stuff already.

(If someone wants to set up Linux "make install"s to use alternatives it would
make sense to put these notes to the user back in.)

Change-Id: Ib7f4655a222ccaee83830a97b213656856cee73e
Reviewed-on: https://code.wireshark.org/review/5622
Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com>