Refine .env.example files across all stacks

- Streamline variable organization and formatting
- Reduce redundant comments and improve clarity
- Maintain all required variables for each stack

docker-compose/dashboards/.env.example

@@ -1,16 +1,11 @@
 # Dashboards Stack Environment Variables
-# These variables are used for Homepage and Homarr
 
-# Base Configuration
-DOMAIN=
 TZ=
-
-# User Configuration
 PUID=
 PGID=
-
-# Directory Configuration
+SERVER_IP=
+SERVER_HOSTNAME=
+DOMAIN=
 STACKS_DIR=
 
-# Homepage Configuration
 HOMEPAGE_ALLOWED_HOSTS=