Index.rst: Add Rafi, Elias, Nicola as further contributors

Documentation/Index.rst

@@ -27,6 +27,9 @@ Quick Form Query Extension
 :Authors:
    Carsten Rose, Benjamin Baer, Marc Egger
 
+:Further Contributors:
+   Rafael Ostertag, Elias Villiger, Nicola Chiapolini
+
 :Email:
    carsten.rose@math.uzh.ch, benjamin.baer@math.uzh.ch, marc.egger@uzh.ch