Typo fix in web service client API overview.

--
Imported using git-svn from
https://dev.csi.cam.ac.uk/svn/lookup/trunk@17

src/java/ws-overview.html

@@ -78,7 +78,7 @@
             <a href="uk/ac/cam/ucs/ibis/client/ClientConnection.html#setPassword(java.lang.String)">
             ClientConnection.setPassword()</a> are not thread safe. These methods
             are regarded as part of the initialisation of the connection, and
-            should typically only be use once on startup. If you need to
+            should typically only be used once on startup. If you need to
             regularly switch between users, then use a separate
             <code>ClientConnection</code> per user or per thread (and separate
             corresponding <code>XxxMethods</code> objects).