build: include {README.md,git-version-gen} into the release tarball

Change-Id: I072b5899ac77326f619d351f17aa78490946f452
diff --git a/Makefile.am b/Makefile.am
index e6ba26d..bb3d753 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -11,8 +11,10 @@
 
 EXTRA_DIST = \
 	.version \
+	README.md \
 	contrib/osmo-hlr.spec.in \
 	debian \
+	git-version-gen \
 	$(NULL)
 
 AM_DISTCHECK_CONFIGURE_FLAGS = \