Use specific links to DefaultAzureCredential (Azure#21477)

Resolves Azure#21460

Author: heaths

sdk/keyvault/Azure.Security.KeyVault.Administration/README.md

@@ -277,7 +277,7 @@ additional questions or comments.
 [admin_client_src]: https://github.com/Azure/azure-sdk-for-net/tree/master/sdk/keyvault/Azure.Security.KeyVault.Administration/src
 [JWK]: https://tools.ietf.org/html/rfc7517
 [nuget]: https://www.nuget.org/
-[DefaultAzureCredential]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/identity/Azure.Identity/README.md
+[DefaultAzureCredential]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/identity/Azure.Identity/README.md#defaultazurecredential
 [logging]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/core/Azure.Core/samples/Diagnostics.md
 [contributing]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/keyvault/Microsoft.Azure.KeyVault/CONTRIBUTING.md
 [coc_faq]: https://opensource.microsoft.com/codeofconduct/faq/

sdk/keyvault/Azure.Security.KeyVault.Certificates/README.md

@@ -334,7 +334,7 @@ This project has adopted the [Microsoft Open Source Code of Conduct][code_of_con
 [hello_world_sample]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/keyvault/Azure.Security.KeyVault.Certificates/samples/Sample1_HelloWorld.md
 [get_cetificates_sample]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/keyvault/Azure.Security.KeyVault.Certificates/samples/Sample2_GetCertificates.md
 [code_of_conduct]: https://opensource.microsoft.com/codeofconduct/
-[DefaultAzureCredential]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/identity/Azure.Identity/README.md
+[DefaultAzureCredential]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/identity/Azure.Identity/README.md#defaultazurecredential
 [contributing]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/keyvault/CONTRIBUTING.md
 [coc_faq]: https://opensource.microsoft.com/codeofconduct/faq/
 [migration_guide]: https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/keyvault/Azure.Security.KeyVault.Certificates/MigrationGuide.md