add fetch-gerrit-patch.sh, tweak READMEs

Change-Id: I6df4f3226af9087ef346de72cbcaa86a4d4d5e13
diff --git a/README b/README
index a3ab68f..65dbf2e 100644
--- a/README
+++ b/README
@@ -52,3 +52,8 @@
 
 Remove osmocom built binaries and headers from given prefix,
 default is /usr/local.
+
+
+=== src/*
+
+Find other useful scripts in src/, see src/README.