minor #3772 [Cookbook][Sessions] some language improvements (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[Cookbook][Sessions] some language improvements

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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f4d40e7 [Cookbook][Sessions] some language improvements

cookbook/session/proxy_examples.rst

@@ -1,5 +1,5 @@
 .. index::
-   single: Sessions, session proxy, proxy
+   single: Sessions, Session Proxy, Proxy
 
 Session Proxy Examples
 ======================
@@ -16,7 +16,7 @@ is injected into the proxy and registered with the session storage driver::
     $session = new Session(new NativeSessionStorage(array(), $proxy));
 
 Below, you'll learn two real examples that can be used for ``YourProxy``:
-encryption of session data and readonly guest session.
+encryption of session data and readonly guest sessions.
 
 Encryption of Session Data
 --------------------------
@@ -56,8 +56,8 @@ Readonly Guest Sessions
 -----------------------
 
 There are some applications where a session is required for guest users, but
-there is no particular need to persist the session. In this case you can
-intercept the session before it writes::
+where there is no particular need to persist the session. In this case you
+can intercept the session before it is written::
 
     use Foo\User;
     use Symfony\Component\HttpFoundation\Session\Storage\Proxy\SessionHandlerProxy;