BUG:0012144 correct the documentation for GetArrayIndex

Per bug # 0012114, the documentation was wrong.

Change-Id: I4386cc01edc6f84f9ca1aa2a02d19ff61d1d4bdf

Common/Core/vtkDataArraySelection.h

@@ -75,7 +75,7 @@ public:
   const char* GetArrayName(int index);
 
   // Description:
-  // Get an index of the array containing name within the enabled arrays
+  // Get an index of the array with the given name.
   int GetArrayIndex(const char *name);
 
   // Description: