Update README with project related information and convert to Markdown

Also, include it in 'make dist' tarballs.

Change-Id: Ia28743b7ea3510097f841f83d2eca2669b4d73ea
diff --git a/Makefile.am b/Makefile.am
index ab8191e..447b148 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5,7 +5,7 @@
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libosmo-ranap.pc
 
-EXTRA_DIST = asn1 .version
+EXTRA_DIST = asn1 .version README.md
 
 BUILT_SOURCES = $(top_srcdir)/.version
 $(top_srcdir)/.version: