Fix subscribe links for Developer Forums doc.

The email-based subscribe links for the Android Developer forums do
not work for two groups (android-discuss, android-beginners) due to
recent changes in those groups. These links need to be changed to
HTML-based subscribe links instead.

For consistency, other links are being changed to use the HTML-based
subscription mechanism as well.

Internal Bug: 2908002

Change-Id: I601b959935584270d6107c4600b28ac5f51359e1
diff --git a/docs/html/resources/community-groups.jd b/docs/html/resources/community-groups.jd
index 72bdf7a..651edbc 100644
--- a/docs/html/resources/community-groups.jd
+++ b/docs/html/resources/community-groups.jd
@@ -87,27 +87,27 @@
 <h3 id="ApplicationDeveloperLists">Application developer mailing lists</h3>
 <ul>
 <li><strong><a href="http://groups.google.com/group/android-developers">android-developers</a></strong>
-(<a href="mailto:android-developers-subscribe@googlegroups.com">subscribe via email</a>)<br>
+(<a href="http://groups.google.com/group/android-developers/subscribe">subscribe</a>)<br>
 You're now an experienced Android application developer. You've grasped the basics of Android app development, you're comfortable using the SDK, now you want to move to advanced topics. Get help here with troubleshooting applications, advice on implementation, and strategies for improving your application's performance and user experience. This is the not the right place to discuss user issues (use android-discuss for that) or beginner questions with the Android SDK (use android-beginners for that).
 </li>
 
 <li><strong><a href="http://groups.google.com/group/android-discuss">android-discuss</a></strong>
-(<a href="mailto:android-discuss-subscribe@googlegroups.com">subscribe via email</a>)<br>
+(<a href="http://groups.google.com/group/android-discuss/subscribe">subscribe</a>)<br>
 The "water cooler" of Android discussion. You can discuss just about anything Android-related here, ideas for the Android platform, announcements about your applications, discussions about Android devices, community resources... As long as your discussion is related to Android, it's on-topic here. However, if you have a discussion here that could belong on another list, you are probably not reaching all of your target audience here and may want to consider shifting to a more targeted list.
 </li>
 
 <li><strong><a href="http://groups.google.com/group/android-ndk">android-ndk</a></strong>
-(<a href="mailto:android-ndk-subscribe@googlegroups.com">subscribe via email</a>)<br>
+(<a href="http://groups.google.com/group/android-ndk/subscribe">subscribe</a>)<br>
 A place for discussing the Android NDK and topics related to using native code in Android applications.
 </li>
 
 <li><strong><a href="http://groups.google.com/group/android-security-discuss">android-security-discuss</a></strong>
-(<a href="mailto:android-security-discuss-subscribe@googlegroups.com">subscribe via email</a>)<br>
+(<a href="http://groups.google.com/group/android-security-discuss/subscribe">subscribe</a>)<br>
 A place for open discussion on secure development, emerging security concerns, and best practices for and by android developers. Please don't disclose vulnerabilities directly on this list, you'd be putting all Android users at risk.
 </li>
 
 <li><strong><a href="http://groups.google.com/group/android-security-announce">android-security-announce</a></strong>
-(<a href="mailto:android-security-announce-subscribe@googlegroups.com">subscribe via email</a>)<br>
+(<a href="http://groups.google.com/group/android-security-announce/subscribe">subscribe</a>)<br>
 A low-volume group for security-related announcements by the Android Security Team.
 </li>
 </ul>