++ fix: update .env.example and README.md, add CreateInitialAdmin command, update docker-compose.yml and entrypoint.sh, remove old CSS file and update manifest.json

.env.example

@@ -8,6 +8,10 @@ APP_URL=http://localhost:8080
 APP_PORT=8080
 SEED_DEV_DATA=false
 RUN_DB_SEED_ON_FIRST_START=true
+ENSURE_INITIAL_ADMIN_ON_EMPTY_DB=true
+INITIAL_ADMIN_NAME=
+INITIAL_ADMIN_EMAIL=
+INITIAL_ADMIN_PASSWORD=
 
 DB_CONNECTION=mysql
 DB_HOST=mariadb