Revert "remove deprecated flag"

This reverts commit d262c89.

Author: Kenneth Reitz

docs/starting/install/linux.rst

@@ -58,7 +58,7 @@ project's directory
 
 .. code-block:: console
 
-    $ virtualenv venv
+    $ virtualenv --distribute venv
 
 To use an environment, run ``source venv/bin/activate``. Your command prompt
 will change to show the active environment. Once you have finished working in