[svn r15038] Added warning about new CSS styles

documentation/installation_guide.html

@@ -254,7 +254,10 @@ directories. You can still recover them from your backup if you have made it.
  overwritten by the next step. To avoid loosing your customisations, always 
  ensure you copy the styles/images under a new name and use and modify the 
  copy, not the original. The original will always be overwritten by newer 
- versions.</font>
+ versions. In Dokeos 1.8.5, we have changed the name of several CSS themes.
+ Backwards compatibility is ensured by the fact that an upgrade only adds the
+new themes, but you should try and use these new themes rather than sticking
+to the old ones which will be deprecated shortly (not maintained).</font>
 <br />
 <p></p>
 <h3>3.2 Upgrading from Dokeos 1.6.x</h3>