add comment in hack/update-*.sh

hack/pin-dependency.sh

@@ -14,6 +14,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# Usage:
+#   hack/pin-dependency.sh $MODULE $SHA-OR-TAG
+#
+# Example:
+#   hack/pin-dependency.sh github.com/docker/docker 501cb131a7b7
+
 set -o errexit
 set -o nounset
 set -o pipefail
@@ -21,12 +27,6 @@ set -o pipefail
 KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
 source "${KUBE_ROOT}/hack/lib/init.sh"
 
-# Usage:
-#   hack/pin-dependency.sh $MODULE $SHA-OR-TAG
-#
-# Example:
-#   hack/pin-dependency.sh github.com/docker/docker 501cb131a7b7
-
 # Explicitly opt into go modules, even though we're inside a GOPATH directory
 export GO111MODULE=on
 # Explicitly clear GOFLAGS, since GOFLAGS=-mod=vendor breaks dependency resolution while rebuilding vendor