docs(api/index): add Oxford comma

Verified grammar at https://owl.english.purdue.edu/owl/resource/607/01/

Author: amarpatel

docs/content/api/index.ngdoc

@@ -6,7 +6,7 @@
 Welcome to the AngularJS API docs page. These pages contain the AngularJS reference materials for version <strong ng-bind="version"></strong>.
 
 The documentation is organized into **{@link guide/module modules}** which contain various components of an AngularJS application.
-These components are {@link guide/directive directives}, {@link guide/services services}, {@link guide/filter filters}, {@link guide/providers providers}, {@link guide/templates templates}, global APIs and testing mocks.
+These components are {@link guide/directive directives}, {@link guide/services services}, {@link guide/filter filters}, {@link guide/providers providers}, {@link guide/templates templates}, global APIs, and testing mocks.
 
 <div class="alert alert-info">
 **Angular Namespaces `$` and `$$`**
@@ -212,7 +212,7 @@ Use ngTouch when developing for mobile browsers/devices.
       {@link ngTouch#service Services / Factories}
     </td>
     <td>
-      The {@link ngTouch.$swipe $swipe} service is used to register and manage mobile DOM events. 
+      The {@link ngTouch.$swipe $swipe} service is used to register and manage mobile DOM events.
     </td>
   </tr>
   <tr>
@@ -252,7 +252,7 @@ Use ngSanitize to securely parse and manipulate HTML data in your application.
 
 ## {@link ngMock ngMock}
 
-Use ngMock to inject and mock modules, factories, services and providers within your unit tests 
+Use ngMock to inject and mock modules, factories, services and providers within your unit tests
 
 <div class="alert alert-info">Include the **angular-mocks.js** file into your test runner for this to work.</div>