Add readme.md + prettier

Author: REDMOND\lakshv

specification/providerhub/resource-manager/Microsoft.ProviderHub/preview/2021-09-01-preview/providerhub.json

@@ -4046,9 +4046,9 @@
       "type": "object",
       "properties": {
         "enabledSubscriptions": {
-          "type":"array",
+          "type": "array",
           "items": {
-            "type":"string"
+            "type": "string"
           }
         }
       },

specification/providerhub/resource-manager/readme.md

@@ -30,6 +30,19 @@ openapi-subtype: rpaas
 tag: package-2020-11-20
 ```
 
+### Tag: package-2021-09-01-preview
+
+These settings apply only when `--tag=package-2021-09-01-preview` is specified on the command line.
+
+```yaml $(tag) == 'package-2021-09-01-preview'
+input-file:
+  - Microsoft.ProviderHub/preview/2021-09-01-preview/providerhub.json
+directive:
+  - suppress: R4009
+    from: providerhub.json
+    reason: This version doesn't support systemData.
+```
+
 ### Tag: package-2021-06-01-preview
 
 These settings apply only when `--tag=package-2021-06-01-preview` is specified on the command line.