chore: fix typos (GoogleCloudPlatform#5690)

## Description

Fixes #<ISSUE-NUMBER>

Note: It's a good idea to open an issue first for discussion.

## Checklist
- [x] I have followed [Sample Guidelines from AUTHORING_GUIDE.MD](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/AUTHORING_GUIDE.md)
- [ ] README is updated to include [all relevant information](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/AUTHORING_GUIDE.md#readme-file)
- [x] **Tests** pass:   `nox -s py-3.6` (see [Test Environment Setup](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/AUTHORING_GUIDE.md#test-environment-setup))
- [x] **Lint** pass:   `nox -s lint` (see [Test Environment Setup](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/AUTHORING_GUIDE.md#test-environment-setup))
- [ ] These samples need a new **API enabled** in testing projects to pass (let us know which ones)
- [ ] These samples need a new/updated **env vars** in testing projects set to pass (let us know which ones)
- [x] Please **merge** this PR for me once it is approved.
- [ ] This sample adds a new sample directory, and I updated the [CODEOWNERS file](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/.github/CODEOWNERS) with the codeowners for this sample

Author: leahecole

composer/rest/get_client_id.py

@@ -55,15 +55,16 @@ def get_client_id(project_id, location, composer_environment):
     # [END composer_get_environment_client_id]
 
 
+# Usage: python get_client_id.py your_project_id your_region your_environment_name
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter)
     parser.add_argument('project_id', help='Your Project ID.')
     parser.add_argument(
-        'location', help='Region of the Cloud Composer environent.')
+        'location', help='Region of the Cloud Composer environment.')
     parser.add_argument(
-        'composer_environment', help='Name of the Cloud Composer environent.')
+        'composer_environment', help='Name of the Cloud Composer environment.')
 
     args = parser.parse_args()
     get_client_id(

composer/rest/get_dag_prefix.py

@@ -48,15 +48,16 @@ def get_dag_prefix(project_id, location, composer_environment):
     # [END composer_get_environment_dag_prefix]
 
 
+# Usage: python get_dag_prefix.py your_project_id your_region your_environment_name
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter)
     parser.add_argument('project_id', help='Your Project ID.')
     parser.add_argument(
-        'location', help='Region of the Cloud Composer environent.')
+        'location', help='Region of the Cloud Composer environment.')
     parser.add_argument(
-        'composer_environment', help='Name of the Cloud Composer environent.')
+        'composer_environment', help='Name of the Cloud Composer environment.')
 
     args = parser.parse_args()
     get_dag_prefix(