Add comment about using SigV4 authentication where possible. (#4298)

* Add comment about using SigV4 authentication where possible.
* Implemented editor suggestion on Cassandra wrapper.

Author: irenepsmith

dotnetv3/Keyspaces/Actions/HelloKeyspaces.cs

@@ -10,7 +10,7 @@ public class HelloKeyspaces
 
     static async Task Main(string[] args)
     {
-        // Set up dependency injection for the Amazon service.
+        // Set up dependency injection for Amazon Keyspaces (for Apache Cassandra).
         using var host = Host.CreateDefaultBuilder(args)
             .ConfigureLogging(logging =>
                 logging.AddFilter("System", LogLevel.Debug)

dotnetv3/Keyspaces/Scenarios/CassandraWrapper.cs

@@ -9,7 +9,10 @@
 namespace KeyspacesScenario;
 
 /// <summary>
-/// Class to perform CRUD methods on a Keyspaces (for Apache Cassandra) database.
+/// Class to perform CRUD methods on an Amazon Keyspaces (for Apache Cassandra) database.
+///
+/// NOTE: This sample uses a plain text authenticator for example purposes only.
+/// Recommended best practice is to use a SigV4 authentication plugin, if available.
 /// </summary>
 public class CassandraWrapper
 {