Fixes for docker compose formatting and missing storage dir

docker-compose.example.yml

@@ -1,19 +1,22 @@
 version: '3.8'
 x-common:
-  database: &db-environment
+  database:
+    &db-environment
     # Do not remove the "&db-password" from the end of the line below, it is important
     # for Panel functionality.
-    MYSQL_PASSWORD: "CHANGE_ME" &db-password
+    MYSQL_PASSWORD: &db-password "CHANGE_ME"
     MYSQL_ROOT_PASSWORD: "CHANGE_ME_TOO"
-  panel: &panel-environment
-    APP_URL: "https://your.domain.here"
+  panel:
+    &panel-environment
+    APP_URL: "https://example.com"
     # A list of valid timezones can be found here: http://php.net/manual/en/timezones.php
     APP_TIMEZONE: "UTC"
     APP_SERVICE_AUTHOR: "noreply@example.com"
     # Uncomment the line below and set to a non-empty value if you want to use Let's Encrypt
     # to generate an SSL certificate for the Panel.
     # LE_EMAIL: ""
-  mail: &mail-environment
+  mail:
+    &mail-environment
     MAIL_FROM: "noreply@example.com"
     MAIL_DRIVER: "smtp"
     MAIL_HOST: "mail"
@@ -37,8 +40,8 @@ services:
       - "/srv/pterodactyl/database:/var/lib/mysql"
     environment:
       <<: *db-environment
-        MYSQL_DATABASE: "panel"
-        MYSQL_USER: "pterodactyl"
+      MYSQL_DATABASE: "panel"
+      MYSQL_USER: "pterodactyl"
   cache:
     image: redis:alpine
     restart: always
@@ -59,14 +62,14 @@ services:
     environment:
       <<: *panel-environment
       <<: *mail-environment
-        DB_PASSWORD: *db-password
-        APP_ENV: "production"
-        APP_ENVIRONMENT_ONLY: "false"
-        CACHE_DRIVER: "redis"
-        SESSION_DRIVER: "redis"
-        QUEUE_DRIVER: "redis"
-        REDIS_HOST: "cache"
-        DB_HOST: "database"
+      DB_PASSWORD: *db-password
+      APP_ENV: "production"
+      APP_ENVIRONMENT_ONLY: "false"
+      CACHE_DRIVER: "redis"
+      SESSION_DRIVER: "redis"
+      QUEUE_DRIVER: "redis"
+      REDIS_HOST: "cache"
+      DB_HOST: "database"
 networks:
   default:
     ipam: