Update WebPush.rst (#726)

Fix typo

docs/WebPush.rst

@@ -121,7 +121,7 @@ The example subscribeUser function is best called in response to a user action,
 
 Server Side logic to create webpush
 ------------------------------
-Is is up to you how to add a view in your django application that can handle a POST of p256dh, auth, registration_id and create a WebPushDevice with those values assoicated with the appropriate user.
+It is up to you how to add a view in your django application that can handle a POST of p256dh, auth, registration_id and create a WebPushDevice with those values assoicated with the appropriate user.
 For example you could use rest_framework
 
 .. code-block:: python