minor #956 Update service_controller.rst (cxj)

This PR was submitted for the master branch but it was merged into the 1.2 branch instead (closes #956).

Discussion
----------

Update service_controller.rst

The word "it's" is a contraction for "it is".  "Its" is a possessive pronoun.

Commits
-------

09a5fe34 Update service_controller.rst

doc/providers/service_controller.rst

@@ -15,7 +15,7 @@ Why would I want to do this?
 
   Using this method, you can inject the actual dependencies required by your
   controller and gain total inversion of control, while still maintaining the
-  lazy loading of your controllers and it's dependencies. Because your
+  lazy loading of your controllers and its dependencies. Because your
   dependencies are clearly defined, they are easily mocked, allowing you to test
   your controllers in isolation.