[ReleasePR powerbidedicated] [PowerBIDedicated] Elaborate description…

… and examples on capacity mode (#1955)

Create to sync Azure/azure-rest-api-specs#16131
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schemas/2021-01-01/Microsoft.PowerBIDedicated.json

@@ -325,7 +325,7 @@
               "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
             }
           ],
-          "description": "The capacity mode."
+          "description": "Specifies the generation of the Power BI Embedded capacity. If no value is specified, the default value 'Gen2' is used. [Learn More](https://docs.microsoft.com/power-bi/developer/embedded/power-bi-embedded-generation-2)."
         }
       },
       "description": "Properties of Dedicated Capacity resource."