Fix C# readme file typo (#11975)

Author: HarveyLink

specification/authorization/resource-manager/readme.csharp.md

@@ -2,7 +2,7 @@
 
 > see https://aka.ms/autorest
 
-This is the AutoRest configuration file for DNS.
+This is the AutoRest configuration file for Authorization.
 
 These settings apply only when `--csharp` is specified on the command line.
 Please also specify `--csharp-sdks-folder=<path to "SDKs" directory of your azure-sdk-for-net clone>`.
@@ -120,4 +120,4 @@ output-folder: $(csharp-sdks-folder)/$(csharp-profile)/Authorization/Management.
 
 batch:
  - tag: profile-hybrid-2020-09-01
- ```
+ ```