Added wsgi-server environment variable EMAIL_FROM to docker-compose.yml and readme

docker-compose.yml

@@ -29,6 +29,7 @@ services:
 #      - EMAIL_HOST_USER=
 #      - EMAIL_HOST_PASSWORD=
 #      - EMAIL_USE_TLS=True
+#      - EMAIL_FROM=no-reply@example.com  #Default sender email address
     ports:
       - '${WSGI_PORT:-8000}:8000'
     networks: