change doc version for ns-3-dev branch

doc/tutorial/source/conf.py

@@ -48,9 +48,9 @@ copyright = u'2010, ns-3 project'
 # built documents.
 #
 # The short X.Y version.
-version = 'ns-3.11'
+version = 'ns-3-dev'
 # The full version, including alpha/beta/rc tags.
-release = 'ns-3.11'
+release = 'ns-3-dev'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.