review required properties for AutomationRunbookReceiver

@nithinpnp - can you review the properties that are listed as required for AutomationRunbookReceiver object on Microsoft.insights/actionGroups? The "name" property is not listed as required but it seems to be required.

Here is the [required list](https://github.com/Azure/azure-rest-api-specs/blob/master/specification/monitor/resource-manager/Microsoft.Insights/stable/2019-06-01/actionGroups_API.json#L670).

This is in response to a customer question that was surfaced through documentation.

Open specification/monitor/resource-manager/Microsoft.Insights/stable/2019-06-01/actionGroups_API.json at the required-property list around line 670 and inspect the AutomationRunbookReceiver definition. Compare the listed requirements with the reported customer behavior; done means the specification accurately represents whether the name property is required.

Written by the indexing model from the issue text.