Update README.md

README.md

@@ -44,7 +44,7 @@ their discussion areas.
 * [Integration of theorem prover libraries](http://kwarc.info/projects/OAF) (in the
   [MathHub System](http://mathhub.info)). #7
 * Active Dokuments and the integration of semantic services into technical/mathematical
-  documents (e.g. for course materials): #9
+  documents (e.g. for course materials): #9 #23
 * Interoperability and integration of mathematical software systems - e.g. computer
   algebra, math data bases, theorem provers (in the
   [OpenDreamKit](http://opendreamkit.org) EU project) #7