Fix badge generator URLs and images, and update
script to generate different alt text for the different button styles.
Also change homepage announce link for blog post.

Change-Id: Ibbdc2e8abad3c218d030299eb60ba5bee75db232
diff --git a/docs/html/index.jd b/docs/html/index.jd
index 2223860..cfd9ff1 100644
--- a/docs/html/index.jd
+++ b/docs/html/index.jd
@@ -20,7 +20,7 @@
     <p>Introducing <strong>Google Play</strong>: An integrated digital content destination where
 users buy and enjoy all of their favorite content in one place. It's the new destination for
 Android apps!</p>
-    <p><a href="http://android-developers.blogspot.com/">Read more &raquo;</a></p>
+    <p><a href="http://android-developers.blogspot.com/2012/03/introducing-google-play.html">Read more &raquo;</a></p>
                                 </div> <!-- end annoucement -->
                             </div> <!-- end annoucement-block -->
                         </div><!-- end topAnnouncement -->