[Doc]: New-AzAutomationSchedule doc doesn't mention that it'll update an existing Schedule even though it will

### Type of issue

Missing information

### Feedback

In both the Synopsis and Description of the cmdlet it states it'll create an Automation Schedule but the API it calls will create or update a schedule. This extra clarity on the cmdlet is important because the Set cmdlet will only let you change 2 properties (Description and IsEnabled) which may cause confusion for how a user is supposed to update all the other properties of a schedule without having to delete it and create it new (along with having to unregister and register it from any runbooks it's linked to).

To ensure the cmdlet would actually update an existing Schedule I had to check the API docs for schedules and then check the code for the command to ensure it was calling the expected endpoint. I could have tested it by just running it but wanted to be sure first. Either of these could have been prevented by the doc just telling me it'd create or update the schedule.

### Page URL

https://learn.microsoft.com/en-us/powershell/module/az.automation/new-azautomationschedule?view=azps-13.1.0

### Content source URL

https://github.com/Azure/azure-powershell/blob/main/src/Automation/Automation/help/New-AzAutomationSchedule.md

### Author

@mikefrobbins

### Document Id

779aca64-73fc-2ffa-44ea-6839fddd1a7e

Open src/Automation/Automation/help/New-AzAutomationSchedule.md and review the Synopsis and Description for New-AzAutomationSchedule. Update both sections to state that the cmdlet creates or updates an Automation Schedule, while preserving the existing explanation of its behavior. Confirm the generated documentation matches the requested clarification.

Written by the indexing model from the issue text.