After Ubuntu server update, Docker API was upgraded to v1.44+, causing
Traefik v2.11 to fail with 'client version 1.24 is too old' error.
Updated Traefik image to v3.6.0 to resolve compatibility issue and
restore ERP site (https://erp.localhost/) functionality.
* 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