Correct wrong cache document link (#35181)

src/Caching/README.md

 # Caching
 
-This area contains distributed cache implementations for Microsoft SQL Server and Redis. See documentation at <https://docs.microsoft.com/en-us/aspnet/core/fundamentals/http-requests#use-polly-based-handlers>.
+This area contains distributed cache implementations for Microsoft SQL Server and Redis. See documentation at <https://docs.microsoft.com/en-us/aspnet/core/performance/caching/distributed?view=aspnetcore-5.0>.
 
 ## Description