[Hub Generated] Review request for Microsoft.Confluent to add version preview/2021-09-01-preview (#16048)

* Adds base for updating Microsoft.Confluent from version preview/2021-03-01-preview to version 2021-09-01-preview

* Updates readme

* Updates API version in new specs and examples

* Fixing spellcheck (#16551)

Author: krishnasriSomepalli

cSpell.json

@@ -834,7 +834,7 @@
             ]
         },
         {
-            "filename": "**/specification/confluent/resource-manager/Microsoft.Confluent/preview/2021-03-01-preview/confluent.json",
+            "filename": "**/specification/confluent/resource-manager/Microsoft.Confluent/preview/*/confluent.json",
             "words": [
                 "orgvalidate"
             ]