Message clarification for #1287 (#1396)

Old message:
> To create a disconnected multiplexer, disable AbortOnConnectFail.

New message proposal:
> Error connecting right now. To allow this multiplexer to continue retrying until it's able to connect, use abortConnect=false in your connection string or AbortOnConnectFail=false; in your code.

src/StackExchange.Redis/ExceptionFactory.cs

@@ -344,7 +344,7 @@ internal static Exception UnableToConnect(ConnectionMultiplexer muxer, string fa
             if (muxer != null)
             {
                 if (muxer.AuthSuspect) sb.Append(" There was an authentication failure; check that passwords (or client certificates) are configured correctly.");
-                else if (!muxer.RawConfig.AbortOnConnectFail) sb.Append(" To create a disconnected multiplexer, disable AbortOnConnectFail.");
+                else if (!muxer.RawConfig.AbortOnConnectFail) sb.Append(" Error connecting right now. To allow this multiplexer to continue retrying until it's able to connect, use abortConnect=false in your connection string or AbortOnConnectFail=false; in your code.");
             }
             if (!string.IsNullOrWhiteSpace(failureMessage)) sb.Append(" ").Append(failureMessage.Trim());