Fixed typo.

pcky · pcky · commit 94cb8728db71 · 2015-04-27T13:04:13.000+02:00
diff --git a/book/installation.rst b/book/installation.rst
@@ -305,7 +305,7 @@ several minutes to complete.
 .. tip::
 
     Symfony provides a command to check whether your project's dependencies
-    contain any know security vulnerability:
+    contain any known security vulnerability:
 
     .. code-block:: bash
 
