add readme

README.md

+# Hammelig - One time shared
+This is Dockerised selfhosted hammelig with traefik
+
+[See Hammelig repository](https://github.com/HemmeligOrg/Hemmelig.app)
+
+## Install
+```bash
+cp .env.sample .env
+# Modify variable in .env in .env
+
+# create volumes directories
+mkdir -p data/hemmelig database
+
+# set permissions (Node user has UID 1000 within the container)
+chown 1000:1000 data/hemmelig database
+
+docker-compose up
+```