#1402 Environment variables for custom image (#1403)

* chore: enhance compose.yaml with variables for customize

* chore: use default blank values for db and redis variables in compose.yaml

* chore: Use env var for HTTP(S) publish ports in overrides

* docs: explain use of environment variables for image customization

* chore: use ERPNEXT_VERSION as default

* docs: fixed spelling errors

overrides/compose.traefik-ssl.yaml

@@ -40,7 +40,7 @@ services:
       # Enable the Dashboard and API
       - --api
     ports:
-      - 443:443
+      - ${HTTPS_PUBLISH_PORT:-443}:443
     volumes:
       - cert-data:/certificates