Update Clang's Getting Involved page

* Downplay cfe-commits as a place where design discussion happens.
  Instead, call it out as a place for historical information.
* Add a link to Discord
* Add a link to Office Hours

Author: AaronBallman

clang/www/get_involved.html

@@ -32,12 +32,12 @@ <h2>Follow what's going on</h2>
 and has a Discourse forum and mailing list:</p>
 
 <ul>
-<li><a href="https://lists.llvm.org/mailman/listinfo/cfe-commits">cfe-commits
-</a> - This list is for patch submission/discussion.</li>
-
 <li><a href="https://discourse.llvm.org/c/clang/6">Clang Frontend Discourse forum</a> -
-This forum is for everything else Clang related (questions and answers, design
-discussions, etc).</li>
+This forum is for discussions related to Clang (questions and answers, design
+discussions, RFCs, etc).</li>
+
+<li><a href="https://discord.gg/xS7Z362">Discord chat</a> - Real-time chat for
+discussions related to Clang (primarily for questions and answers).</li>
 
 <li>Regular meetings are held on the
 <a href="https://drive.google.com/file/d/1S7V0MHP4xMs1yUQ9Gv9LHn5bwDfFVapn/view?usp=sharing">
@@ -50,16 +50,23 @@ <h2>Follow what's going on</h2>
 here<a>.
 </li>
 
+<li><a href="https://llvm.org/docs/GettingInvolved.html#office-hours">Clang office hours</a> -
+People within the community hold dedicated office hours at different points
+during the month, which is a great way opportunity for getting questions
+answered, having more in-depth design discussions, or learning about what's
+going on in the community in general.</li>
+
+<li><a href="https://lists.llvm.org/mailman/listinfo/cfe-commits">cfe-commits
+</a> - Historical record of commits to Clang and contains early community patch
+review commentary.</li>
+
 </ul>
 
 <p>The most common way to talk with other developers on the project is through
 the <a href="https://discourse.llvm.org/c/clang/6">Clang Frontend Discourse forum
-</a>.  The clang forum is a very friendly place and we welcome
-newcomers.  In addition to the forum, a significant amount of design
-discussion takes place on the <a
-href="https://lists.llvm.org/mailman/listinfo/cfe-commits">cfe-commits mailing
-list</a>.  All of these lists have archives, so you can browse through previous
-discussions or follow the list development on the web if you prefer.</p>
+</a>. The clang forum is a very friendly place and we welcome newcomers. The
+forum is archived so you can browse through previous discussions or follow
+development on the web if you prefer.</p>
 
 <p>If you're looking for something to work on, check out our <a
 href="OpenProjects.html">Open Projects</a> page or look through the <a