Adding stem to the projects page

Stem is far enough along that it's useful to users, and should have a spot on
the projects page. Also revising the volunteer page links to point to its
readthedocs page, which is presently our homepage.

getinvolved/en/volunteer.wml

@@ -550,9 +550,9 @@ meetings around the world.</li>
     </p>
     
     <a id="project-stem"></a>
-    <h3><a href="https://trac.torproject.org/projects/tor/wiki/doc/stem">Stem</a> (<a
+    <h3><a href="https://stem.readthedocs.org/en/latest/index.html">Stem</a> (<a
     href="https://gitweb.torproject.org/stem.git">code</a>, <a
-    href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Stem&order=priority">bug
+    href="https://trac.torproject.org/projects/tor/wiki/doc/stem/bugs">bug
     tracker</a>)</h3>
     
     <p>

projects/en/projects.wml

@@ -63,6 +63,11 @@ preconfigured so that everything is safely routed through Tor and leaves no
 trace on the local system.</p>
 </div></div>
 
+<div class="projectbox">
+<a href="https://stem.readthedocs.org/en/latest/index.html"><img class="icon" src="$(IMGROOT)/icon-stem.jpg" alt="Stem Icon" width="75" height="75"></a>
+<div class="projectdesc"><div class="name"><a href="https://stem.readthedocs.org/en/latest/index.html">Stem</a></div>
+<p>Python library for libraries and scripts that interact with Tor.</p>
+</div></div>
 
 <div class="projectbox">
 <a href="<page projects/onionoo>"><img class="icon" src="$(IMGROOT)/icon-TorStatus.jpg" alt="Onionoo Icon" width="75" height="75"></a>