[mlir][docs] Update documentation for vector.multi_reduction. NFC (llvm#99668)

Author: obtuseangleAZ

mlir/include/mlir/Dialect/Vector/IR/VectorOps.td

@@ -300,9 +300,9 @@ def Vector_MultiDimReductionOp :
 
     ```mlir
     %1 = vector.multi_reduction <add>, %0, %acc0 [1, 3] :
-      vector<4x8x16x32xf32> into vector<4x16xf32>
+      vector<4x8x16x32xf32> to vector<4x16xf32>
     %2 = vector.multi_reduction <add>, %1, %acc1 [0, 1] :
-      vector<4x16xf32> into f32
+      vector<4x16xf32> to f32
     ```
   }];
   let builders = [