move some configuration into environment vars

.env.example

@@ -0,0 +1,18 @@
+# SECURITY WARNING: keep the secret key used in production secret!
+export SECRET_KEY="7(2w1sedok=aznpq)ta1mc4i%4h=xx@hxwx*o57ctsuml0x%fr"
+
+# SECURITY WARNING: don't run with debug turned on in production!
+export DEBUG=true
+
+export DOMAIN=your.domain.here
+
+## Leave unset to allow all hosts
+# export ALLOWED_HOSTS="localhost,127.0.0.1,[::1]"
+
+export OL_URL="https://openlibrary.org"
+
+## Database backend to use.
+## Default is postgres, use sqlite is for dev quickstart only (NOT production!!!)
+export FEDIREADS_DATABASE_BACKEND=postgres
+
+export MEDIA_ROOT="images/"