ndb - bug#21400

  Fix docs for NdbOpertation::sub_reg


ndb/include/ndbapi/NdbOperation.hpp:
  Fix docs for sub_reg

ndb/include/ndbapi/NdbOperation.hpp

@@ -445,7 +445,7 @@ public:
 
   /**
    * Interpreted program instruction:
-   * Substract RegSource1 from RegSource2 and put the result in RegDest.
+   * Substract RegSource2 from RegSource1 and put the result in RegDest.
    *
    * @param RegSource1   First register.
    * @param RegSource2   Second register.