src/www/gf-web-api.t2t: Web API docs rescued from the Google Code graveyard

This is the GFWebServiceAPI.wiki rescued from the Google Code Archive,
converted to txt2tags format, with an updated introduction.

src/www/index.html

@@ -31,7 +31,7 @@
   <li><a href="gfse/about.html">About the online grammar editor</a>
   <li><a href="translator/about.html">About the simple translation tool</a>
   <li><a href="gf-web-api-examples.html">PGF web service API examples</a>
-  <li><a href="http://code.google.com/p/grammatical-framework/wiki/GFWebServiceAPI">PGF web service API documentation</a>
+  <li><a href="gf-web-api.html">PGF web service API documentation</a>
   <li><a href="gf-cloud-api.html">GF Cloud Service API</a>
 </ul>