add links to Porter examples

Author: mikespub

README.md

@@ -80,4 +80,6 @@ $ porter upgrade python-app --reference mikespub/python-app:v0.3.1 --allow-docke
 $ porter uninstall python-app --allow-docker-host-access
 ```
 
+See https://github.com/getporter/docker-compose-mixin/tree/main/examples
+and https://github.com/getporter/porter/tree/main/examples/dockerapp