README.md: Mention user manual

Change-Id: I6e40166a2ed7ba9f352b466ce85651e20da591e9
diff --git a/README.md b/README.md
index ad333d5..db294c6 100644
--- a/README.md
+++ b/README.md
@@ -72,6 +72,15 @@
 We are using a gerrit-based patch review process explained at
 <https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit>
 
+
+Manual
+------
+p
+Please see the sphinx based documentation in the 'docs' sub-directory
+of the source.  A PDF rendering of the user manual is available from
+<https://ftp.osmocom.org/docs/latest/osmosmlc-usermanual.pdf>
+
+
 Usage
 -----