Update README.md

README.md

 # mastodon
 Mastodon application for libre.sh
 
+## Copy configuration
+
+    cp .env.production.sample .env.production
+
 ## Generate secrets
 
+Do this three times:
+
     docker compose run --rm app bundle exec rake secret
 
+Fill the generated keys into the blank secrets in `.env.production`.
+
 ## Migrate database
 
     docker compose run --rm app bundle exec rake db:migrate