Provide Microsoft.AspNetCore.DataProtection.StackExchangeRedis package README (dotnet#57825)

Author: MackinnonBuck

src/DataProtection/StackExchangeRedis/src/PACKAGE.md

@@ -0,0 +1,34 @@
+## About
+
+`Microsoft.AspNetCore.DataProtection.StackExchangeRedis` allows storing data protection keys in a Redis cache.
+
+> [!WARNING]
+> Only Redis versions supporting [Redis Data Persistence](https://learn.microsoft.com/azure/azure-cache-for-redis/cache-how-to-premium-persistence) should be used to store keys. [Azure Blob storage](https://learn.microsoft.com/azure/storage/blobs/storage-blobs-introduction) is persistent and can be used to store keys. For more information, see [this GitHub issue](https://github.com/dotnet/AspNetCore/issues/13476).
+
+## How to Use
+
+To use `Microsoft.AspNetCore.DataProtection.StackExchangeRedis`, follow these steps:
+
+### Installation
+
+```shell
+dotnet add package Microsoft.AspNetCore.DataProtection.StackExchangeRedis
+```
+
+### Configuration
+
+To configure data protection key storage on Redis, call one of the `PersistKeysToStackExchangeRedis` overloads:
+
+```csharp
+var redis = ConnectionMultiplexer.Connect("<URI>");
+builder.Services.AddDataProtection()
+    .PersistKeysToStackExchangeRedis(redis, "DataProtection-Keys");
+```
+
+## Additional Documentation
+
+For additional documentation and examples, refer to the [official documentation](https://learn.microsoft.com/aspnet/core/security/data-protection/implementation/key-storage-providers#redis) on the Redis key storage provider.
+
+## Feedback &amp; Contributing
+
+`Microsoft.AspNetCore.DataProtection.StackExchangeRedis` is released as open-source under the [MIT license](https://licenses.nuget.org/MIT). Bug reports and contributions are welcome at [the GitHub repository](https://github.com/dotnet/aspnetcore).