feat: add rpq label into include

Author: suvorovrain

include/LAGraphX.h

@@ -167,8 +167,20 @@ GrB_Info LAGraph_RPQMatrix(
     RpqMatrixPlan *plan,
      char *msg
     );
+
 LAGRAPHX_PUBLIC
 GrB_Info LAGraph_RpqMatrix_initialize();
+
+LAGRAPHX_PUBLIC
+GrB_Info LAGraph_RPQMatrix_label
+(
+    GrB_Matrix *mat, 
+    GrB_Index x,
+    GrB_Index i, 
+    GrB_Index j
+) ;
+
+
 LAGRAPHX_PUBLIC
 int LAGraph_SWrite_HeaderStart  // write the first part of the JSON header
 (