Add prominent note about mailing list, etc.

Fixes #253

documentation/_templates/index.html

@@ -57,6 +57,18 @@ <h1>FiPy: A Finite Volume PDE Solver Using Python</h1>
   <a href="/cgi-bin/redirect.py?url=http://dx.doi.org/10.1109/MCSE.2009.52"><code>doi:10.1109/MCSE.2009.52</code></a>,
   <a href="/cgi-bin/redirect.py?url=http://www.ctcms.nist.gov/fipy"><code>http://www.ctcms.nist.gov/fipy</code></a></p>
   </div>
+  <div class="admonition seealso">
+  <p class="first admonition-title">Other sources of information:</p>
+  <p>For questions not answered here, please check the 
+  <a href="{{ pathto('documentation/MAIL') }}">mailing list</a>,
+  open an issue on the
+  <a href="/cgi-bin/redirect.py?url=https://github.com/usnistgov/fipy/issues">issue tracker</a>,
+  or ask a question on 
+  <a href="/cgi-bin/redicrect.py?https://stackoverflow.com/questions/tagged/fipy">StackOverflow</a>.</p>
+  <p>We encourage you to review the 
+  <a href="https://www.mail-archive.com/fipy@nist.gov/">mailing list archive</a> 
+  before posting a question.</p>
+  </div>
  {% block tables %}
    <h2>Documentation</h2>
    <table class="contentstable" align="center"><tr>