[MLIR] Improve tutorial to make it clear that `walk()` is visiting the root op (NFC)
diff --git a/mlir/docs/Tutorials/UnderstandingTheIRStructure.md b/mlir/docs/Tutorials/UnderstandingTheIRStructure.md
index 30b50cb..f7c62f2 100644
--- a/mlir/docs/Tutorials/UnderstandingTheIRStructure.md
+++ b/mlir/docs/Tutorials/UnderstandingTheIRStructure.md
@@ -178,7 +178,7 @@
to traverse the IR in a nested fashion. To this end MLIR exposes the `walk()`
helper on `Operation`, `Block`, and `Region`. This helper takes a single
argument: a callback method that will be invoked for every operation recursively
-nested under the provided entity.
+nested under the provided entity (as well as this initial operation).
```c++
// Recursively traverse all the regions and blocks nested inside the function
