Update tye.yaml (#833)

This was made before we started using connectionString.

samples/mongo-sample/tye.yaml

@@ -9,6 +9,7 @@ services:
       value: example
   bindings:
     - port: 27017
+      connectionString: "mongodb://${host}:${port}"
 - name: mongo-express
   image: mongo-express
   bindings:
@@ -19,4 +20,4 @@ services:
     - name: ME_CONFIG_MONGODB_ADMINUSERNAME
       value: root
     - name: ME_CONFIG_MONGODB_ADMINPASSWORD
-      value: example
+      value: example