[Resource] `/subscriptions/{subscriptionId}/locations`: Document lags behind swagger

The latest stable API version for `/subscriptions/{subscriptionId}/locations` is `2021-01-01`:

https://github.com/Azure/azure-rest-api-specs/blob/e0a8a42064db5ad298a3f660805d65283c07aca2/specification/resources/resource-manager/Microsoft.Resources/stable/2021-01-01/subscriptions.json#L37

but the public document is still for `2020-01-01`:

https://learn.microsoft.com/en-us/rest/api/resources/subscriptions/list-locations


which I think is generated from https://github.com/Azure/azure-rest-api-specs/blob/e0a8a42064db5ad298a3f660805d65283c07aca2/specification/resources/resource-manager/Microsoft.Resources/stable/2020-01-01/subscriptions.json#L62

This makes new query parameter `includeExtendedLocations` missing from the document:

https://github.com/Azure/azure-rest-api-specs/blob/e0a8a42064db5ad298a3f660805d65283c07aca2/specification/resources/resource-manager/Microsoft.Resources/stable/2021-01-01/subscriptions.json#L52-L59

Compare the 2020-01-01 and 2021-01-01 subscriptions.json files linked in the issue, then check the linked public REST API documentation. Confirm how the document is generated and update the relevant source so the 2021-01-01 version and includeExtendedLocations parameter are reflected publicly.

Written by the indexing model from the issue text.