docs: add top-level explanation of the repo and pointer to current Countdash repo

Author: tgross

README.md

@@ -2,3 +2,9 @@
 
 This repository contains examples of various ways of making use of Nomad's [Consul Connect integration](https://www.nomadproject.io/docs/integrations/consul-connect/).
 
+* `connect-native`: An example service implementing Connect Native.
+* `grpc-checks`: An example service that exposes a gRPC healthcheck endpoint.
+* `ingress-gateway`: Nomad job specifications demonstrating how to configure a Connect Ingress Gateway.
+* `terminating-gateway`: A Nomad job specification demonstrating how to configure a Connect Terminating Gateway.
+
+Looking for Countdash? You can find it here: https://github.com/hashicorp/demo-consul-101/tree/main/services