add some basic env vars info to README

README.md

@@ -4,6 +4,30 @@ Calendaring app for shift-worker shift tracking, with support for CSV export and
 
 Written in Elixir & Phoenix LiveView, with Bootstrap v5.
 
+## Production
+
+To run in production, you'll need to provide several environment variable values:
+
+```bash
+MIX_ENV=prod \
+PHX_SERVER=true \
+DB_SOCK=[postgres unix socket path] \
+DB_NAME=[postgres db name] \
+DB_USER=[postgres db user] \
+DB_PASS=[postgres db user password] \
+SECRET_KEY_BASE=[phoenix secret key base] \
+PHX_HOST=[server fqdn (e.g., shift.73k.us)] \
+SMTP_RELAY=[smtp server] \
+SMTP_PORT=[smtp port] \
+SMTP_USER=[smtp username] \
+SMTP_PASS=[smtp user password] \
+MAIL_REPLY_TO=reply@73k.us \
+MAIL_FROM_FRIENDLY=Shift73k \
+MAIL_FROM_ADDR=shift73k@73k.us \
+ALLOW_REG=[open for registration? true/false] \
+iex -S mix phx.server
+```
+
 ## TODO
 
 - [X] ~~*Proper modal to delete shifts?*~~ [2022-08-14]