Updated README for Identity (#42689)

Added Cosmos DB Provider listings.

Author: toiyabe

src/Identity/README.md

@@ -40,7 +40,10 @@ The previous versions of Identity for MVC5 and lower, previously available on Co
 **IMPORTANT:** Extensions are built by a variety of sources and not maintained as part of the ASP.NET Identity project. When considering a third party provider, be sure to evaluate quality, licensing, compatibility, support, etc. to ensure they meet your requirements.
 
 * [ASP.NET Identity Azure Table Storage Provider](https://dlmelendez.github.io/identityazuretable/)
-* [ASP.NET Identity CosmosDB SQL Provider](https://github.com/dlmelendez/identitycosmosdb)
+* ASP.NET Identity Cosmos DB Providers:
+  * [By Dave Melendez](https://github.com/dlmelendez/identitycosmosdb)
+  * [By Eric Kauffman](https://github.com/CosmosSoftware/AspNetCore.Identity.CosmosDb)
+  * [By Piero De Tomi](https://github.com/pierodetomi/efcore-identity-cosmos)
 * ASP.NET Identity MongoDB Providers:
   * [By Tugberk Ugurlu](https://github.com/tugberkugurlu/AspNetCore.Identity.MongoDB)
   * [By Alexandre Spieser](https://github.com/alexandre-spieser/AspNetCore.Identity.MongoDbCore)