add lighttpd example config

contrib/lighttpd/radicale.conf

@@ -0,0 +1,6 @@
+server.modules += ( "mod_proxy" , "mod_setenv" )
+
+$HTTP["url"] =~ "^/radicale/" {
+  proxy.server = ( "" => (( "host" => "127.0.0.1", "port" => "5232" )) )
+  setenv.add-request-header = ( "X-Script-Name" => "/radicale" )
+}