azurefiles: add --azurefiles-use-az and --azurefiles-disable-instance-discovery

Adds additional authentication options from azureblob to azurefiles as well

See rclone#8078

docs/content/azurefiles.md

@@ -206,6 +206,13 @@ If the resource has multiple user-assigned identities you will need to
 unset `env_auth` and set `use_msi` instead. See the [`use_msi`
 section](#use_msi).
 
+If you are operating in disconnected clouds, or private clouds such as
+Azure Stack you may want to set `disable_instance_discovery = true`.
+This determines whether rclone requests Microsoft Entra instance
+metadata from `https://login.microsoft.com/` before authenticating.
+Setting this to `true` will skip this request, making you responsible
+for ensuring the configured authority is valid and trustworthy.
+
 ##### Env Auth: 3. Azure CLI credentials (as used by the az tool)
 
 Credentials created with the `az` tool can be picked up using `env_auth`.
@@ -288,6 +295,13 @@ be explicitly specified using exactly one of the `msi_object_id`,
 
 If none of `msi_object_id`, `msi_client_id`, or `msi_mi_res_id` is
 set, this is is equivalent to using `env_auth`.
+	
+#### Azure CLI tool `az` {#use_az}
+Set to use the [Azure CLI tool `az`](https://learn.microsoft.com/en-us/cli/azure/)
+as the sole means of authentication.
+Setting this can be useful if you wish to use the `az` CLI on a host with
+a System Managed Identity that you do not want to use.
+Don't set `env_auth` at the same time.
 
 {{< rem autogenerated options start" - DO NOT EDIT - instead edit fs.RegInfo in backend/azurefiles/azurefiles.go then run make backenddocs" >}}
 ### Standard options