add comment in several hack/ sh scripts.

hack/benchmark-go.sh

@@ -14,6 +14,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# This script runs `make test` command with some args for benchmark test.
+# The "true" target of this makerule is `hack/make-rules/test.sh`.
+# Args:
+#   WHAT: Directory names to test.  All *_test.go files under these
+#     directories will be run.  If not specified, "everything" will be tested.
+# Usage: `hack/benchmark-go.sh`.
+# Example: `hack/benchmark-go.sh WHAT=./pkg/kubelet`.
+
 set -o errexit
 set -o nounset
 set -o pipefail

hack/build-cross.sh

@@ -15,6 +15,12 @@
 # limitations under the License.
 
 # This script is a vestigial redirection.  Please do not add "real" logic.
+# The "true" target of this makerule is `hack/make-rules/cross.sh`.
+
+# This script runs `make cross` command.
+# The command sets up a go workspace locally and builds all for all appropriate
+# platforms.
+# Usage: `hack/build-cross.sh`.
 
 set -o errexit
 set -o nounset

hack/build-go.sh

@@ -16,6 +16,15 @@
 
 # This script is a vestigial redirection.  Please do not add "real" logic.
 
+# This script runs `make all` command.
+# The command compiles all Makefile configs.
+# Args:
+#   WHAT: Directory names to build.  If any of these directories has a 'main'
+#     package, the build will produce executable files under $(OUT_DIR)/go/bin.
+#     If not specified, "everything" will be built.
+# Usage: `hack/build-go.sh`.
+# Example: `hack/build-go.sh WHAT=cmd/kubelet`.
+
 set -o errexit
 set -o nounset
 set -o pipefail

hack/e2e-node-test.sh

@@ -15,6 +15,15 @@
 # limitations under the License.
 
 # This script is a vestigial redirection.  Please do not add "real" logic.
+# The "true" target of this makerule is `hack/make-rules/test-e2e-node.sh`.
+
+# This script runs `make test-e2e-node` command.
+# The command builds and runs node end-to-end tests.
+# Args:
+#  FOCUS: Regexp that matches the tests to be run.  Defaults to "".
+#  SKIP: Regexp that matches the tests that needs to be skipped.  Defaults
+# Usage: `hack/e2e-node-test.sh `.
+# Example: `hack/e2e-node-test.sh FOCUS=Kubelet SKIP=container`.
 
 set -o errexit
 set -o nounset

hack/get-build.sh

@@ -14,6 +14,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# This script runs `curl` command to get the kubernetes build file.
+# Version number or publication is either a proper version number'
+# (e.g. "v1.0.6", "v1.2.0-alpha.1.881+376438b69c7612") or a version'
+#  publication of the form <bucket>/<version> (e.g. "release/stable",'
+# "ci/latest-1").'
+
+# Usage `hack/get-build.sh [Version]`.
+# Example `hack/get-build.sh v1.16.4`.
+
 set -o errexit
 set -o nounset
 set -o pipefail