Update README for new env structure

README.md

@@ -24,9 +24,9 @@ git submodule update --init
 We use [Docker Compose](https://docs.docker.com/compose/) to containerize each service and keep all our dependencies in order. Cantus Ultimus is compatible with Docker Compose > 2.8.
 
 ### The `.env` file
-The build process relies on environment variables specified in the `.env` file, which is located at the root of the repository. 
+The build process relies on environment variables specified in an `.env` file located at the root of the repository. A sample of this file, `.env.sample`, is provided.
 
-You must make two modifications to this file before the docker containers will build.  Both `POSTGRES_PASSWORD` and `RABBIT_PASSWORD` should be uncommented and set with secure passwords.
+Make a copy of `.env.sample` and name it `.env`. You must make two modifications to this file before the docker containers will build.  Both `POSTGRES_PASSWORD` and `RABBIT_PASSWORD` should be uncommented and set with secure passwords.
 
 #### Handling `postgres` authentication issues