Previous content in README file is actually a description of the TRXD
and TRXC protocols, and it has already been moved to the User Manual
some time ago. INSTALLATION contained README related information, but it
was really out of date.
So this commit basically drops those two files and provides a new
README.md with content taken from Osmocom's OsmoTRX project wiki page.
Change-Id: I3df00799ce80aa4af43225e69a408ba2cbc444db