Revise CK_NullToPointer comment

This addresses a post-commit review comment in https://github.com/llvm/llvm-project/pull/137364#discussion_r2064772853.
diff --git a/clang/include/clang/AST/OperationKinds.def b/clang/include/clang/AST/OperationKinds.def
index d33d608..c2dca89 100644
--- a/clang/include/clang/AST/OperationKinds.def
+++ b/clang/include/clang/AST/OperationKinds.def
@@ -119,8 +119,7 @@
 CAST_OPERATION(FunctionToPointerDecay)
 
 /// CK_NullToPointer - Null pointer constant to pointer, ObjC
-/// pointer, or block pointer. The result of this conversion can
-/// still be a null pointer constant if it has type std::nullptr_t.
+/// pointer, block pointer, or std::nullptr_t.
 ///   (void*) 0
 ///   void (^block)() = 0;
 CAST_OPERATION(NullToPointer)