renamed non terminal in arm grammar

psGrammar/demos/arm.jsgf

 #JSGF V1.0;
 grammar arm;
 
-public <command> = [meka|floka] <cmd> <obj>;
+public <command> = [meka|floka] <cmd> <arm>;
 
 <cmd> =  (use | grasp with) your ;
-<obj> =  left arm | right arm ;
+<arm> =  left arm | right arm ;