Fixed typo and removed extra space

Author: scottwarren

components/http_foundation/sessions.rst

@@ -14,9 +14,10 @@ implementation of :class:`Symfony\\Component\\HttpFoundation\\Session\\SessionIn
 
 .. caution::
 
-   Make sure your Sessions aren't already initliazed (which in Symfony is
-   done automatically),  as initializing the Session object causes the
-   session to be started, which can lead to unexpected errors.
+   Make sure your Sessions aren't already initliazed (which is done
+   automatically in the full-stack framework), as initializing the
+   Session object causes the session to be started, which can lead
+   to unexpected errors.
 
 Quick example::