Using enum_choice_list to specify allowed values for parameters.

[Prasanna-Padmanabhan]

---

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• The PR has modified HISTORY.rst describing any customer-facing, functional changes. Note that this does not include changes only to help content. (see Modifying change log).

Command Guidelines

• Each command and parameter has a meaningful description.
• Each new command has a test.

(see Authoring Command Modules)

[azuresdkci]

View a preview at https://prompt.ws/r/Azure/azure-cli/4991
This is an experimental preview for @microsoft.com users.
(It may take a minute or two for your instance to be ready)
Email feedback to 'azfeedback' with subject 'Prompt Feedback'.