Merge pull request kubernetes#46269 from xiangpengzhao/fix-make-helpinfo

Automatic merge from submit-queue

Update examples in Makefile with WHAT arguments changed.

**What this PR does / why we need it**:
The examples `make check WHAT` and `make vet WHAT` in Makefile don't work anymore. This PR updates them.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
xref: kubernetes/community#327, kubernetes/community#296, kubernetes#39433

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```

build/root/Makefile

@@ -153,7 +153,7 @@ define CHECK_TEST_HELP_INFO
 # Example:
 # make check
 # make test
-# make check WHAT=pkg/kubelet GOFLAGS=-v
+# make check WHAT=./pkg/kubelet GOFLAGS=-v
 endef
 .PHONY: check test
 ifeq ($(PRINT_HELP),y)
@@ -333,7 +333,7 @@ define VET_HELP_INFO
 #
 # Example:
 # make vet
-# make vet WHAT=pkg/kubelet
+# make vet WHAT=./pkg/kubelet
 endef
 .PHONY: vet
 ifeq ($(PRINT_HELP),y)