Fix typo

Signed-off-by: Hu Shuai <hus.fnst@cn.fujitsu.com>

tools/run_tests/xds_k8s_test_driver/README.md

@@ -71,7 +71,7 @@ disturbances.
 ```sh
 # Help
 python -m tests.baseline_test --help
-python -m tests.baseline_test --helpfull
+python -m tests.baseline_test --helpful
 
 # Run on grpc-testing cluster
 python -m tests.baseline_test \
@@ -85,7 +85,7 @@ python -m tests.baseline_test \
 ```sh
 # Help
 python -m tests.security_test --help
-python -m tests.security_test --helpfull
+python -m tests.security_test --helpful
 
 # Run on grpc-testing cluster
 python -m tests.security_test \

tools/run_tests/xds_k8s_test_driver/bin/run_channelz.py

@@ -26,7 +26,7 @@ Typical usage examples:
     python -m bin.run_channelz --flagfile=config/local-dev.cfg --security=mtls_error
 
     # More information and usage options
-    python -m bin.run_channelz --helpfull
+    python -m bin.run_channelz --helpful
 """
 import hashlib
 import logging

tools/run_tests/xds_k8s_test_driver/bin/run_td_setup.py

@@ -28,7 +28,7 @@ Typical usage examples:
     python -m bin.run_td_setup --flagfile=config/local-dev.cfg --security=mtls
 
     # More information and usage options
-    python -m bin.run_td_setup --helpfull
+    python -m bin.run_td_setup --helpful
 """
 import logging
 import uuid