Update 'README.md'

README.md

@@ -12,6 +12,7 @@ and
 1. Install Docker, docker-compose, and git
 2. Create a new repository in Gitea, using this repository as a template
 3. Clone the new repository
+4. Copy `.env.sample` to `.env`
 4. Copy `src/.env.example` to `src/.env`
 5. Run `docker-compose up`