libtraceevent: Add README

Add a README file that describes where the repositories are, how to build
and install the library, and how to ask questions and contribute.

Link: https://lore.kernel.org/linux-trace-devel/20201210121303.69b0ca80@gandalf.local.home

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
1 file changed