update readme

Author: adamlacombe

README.md

@@ -1 +1,8 @@
 # self-hosted-unpkg
+
+## How to run
+Create .env file. (see sample.env) and run:
+
+```bash
+docker run -it --rm -p 443:443 -p 80:80 -v /local/path/to/cache:/usr/src/app/cache -v /local/path/to/ssl/acme:/usr/src/app/acme --env-file ./.env --name self-hosted-unpkg interactivetraining/self-hosted-unpkg
+```