Add region in provider.yaml

region is required resource type for kind Provider
of Alibaba Cloud or it will raise error message:
error: the server doesn't have a resource type "region"

Signed-off-by: zzxwill <zzxwill@gmail.com>

docs/getting-started/install-configure.md

@@ -354,6 +354,7 @@ spec:
     namespace: crossplane-system
     name: alibaba-creds
     key: credentials
+  region: cn-beijing
 ```
 
 Then apply it: