add links to environment variable documentation in config files and README

README.md

@@ -48,6 +48,8 @@ To run the app yourself, you'll need the following installed:
 
 To run the application once you've cloned this repo, you should be able to just run `bin/dev`; that should set up the database, perform migrations, install dependencies, and then make the application available at <http://127.0.0.1:5000>.
 
+If you want to configure optional features, set the appropriate [environment variables](https://manyfold.app/sysadmin/configuration.html) in a file called `.env`. See `env.example` for a template file. Note that the required environment variables in the documentation are not needed in development mode, due to the use of SQLite instead of PostgreSQL.
+
 ### Coding standards
 
 ![Code Climate maintainability](https://img.shields.io/codeclimate/maintainability/manyfold3d/manyfold)

docker-compose.example.yml

@@ -11,9 +11,8 @@ services:
       DATABASE_URL: postgresql://manyfold:password@db/manyfold?pool=5
       SECRET_KEY_BASE: a_nice_long_random_string
       REDIS_URL: redis://redis:6379/1
-      # RAILS_RELATIVE_URL_ROOT: /manyfold # Sets the root of the app to /manyfold useful for reverse proxies with nginx
-      # MULTIUSER: enabled # Uncomment to enable multiuser mode
-      # REGISTRATION: enabled # If using multiuser mode, uncomment to let any visitor sign up
+      # For details of other optional environment variables, including features such
+      # as multiuser mode, visit https://manyfold.app/sysadmin/configuration.html
     depends_on:
       - db
       - redis

env.example

@@ -0,0 +1,4 @@
+# MULTIUSER: enabled
+# REGISTRATION: enabled
+# For details of other optional environment variables, including features such
+# as multiuser mode, visit https://manyfold.app/sysadmin/configuration.html