added drinks in roboNurse

ps-grammar/roboNurse/roboNurse.jsgf

@@ -9,3 +9,7 @@ public <root> = [tobi] [please] (<command>);
 <pillsspec> = [i need] [the] <properties> (one|bottle);
 
 <properties> = (left most|right most|blue|red|green|big|small);
+<aspirin>=aspirin;
+<milk> = milk;
+<coffee>=coffee;
+<coke> = coke;