docs(upgrade): rename Angular 2 to Angular (#3169)

Author: rsreimer

public/docs/ts/latest/guide/upgrade.jade

@@ -213,7 +213,7 @@ include ../_util-fns
 
   The `upgrade` module in Angular is a very useful tool for upgrading
   anything but the smallest of applications. With it we can mix and match
-  AngularJS and 2 components in the same application and have them interoperate
+  AngularJS and Angular components in the same application and have them interoperate
   seamlessly. That means we don't have to do the upgrade work all at once,
   since there's a natural coexistence between the two frameworks during the
   transition period.
@@ -1115,7 +1115,7 @@ code-example(format="").
   that we want to load. Since we're bootstrapping the app through
   an `UpgradeModule`, we're actually now running the app as a **hybrid app**.
 
-  This means we are now running both AngularJS and 2 at the same time. That's pretty
+  This means we are now running both AngularJS and Angular at the same time. That's pretty
   exciting! We're not running any actual Angular components yet though,
   so let's do that next.
 
@@ -1210,7 +1210,7 @@ code-example(format="").
   Now that we are loading `phone.service.ts` through an import that is resolved
   by SystemJS, we should **remove the <script> tag** for the service from `index.html`.
   This is something we'll do to all our components as we upgrade them. Simultaneously
-  with the AngularJS to 2 upgrade we're also migrating our code from scripts to modules.
+  with the AngularJS to Angular upgrade we're also migrating our code from scripts to modules.
 
   At this point we can switch our two components to use the new service
   instead of the old one. We `$inject` it as the downgraded `phone` factory,