LDAP Docker variables

The docker-compose.yaml is missing the 4 LDAP Mapping variables

https://github.com/fiftin/ansible-semaphore-docs/blob/main/administration-guide/installation.md#docker

SEMAPHORE_LDAP_MAPPING_DN
SEMAPHORE_LDAP_MAPPING_USERNAME
SEMAPHORE_LDAP_MAPPING_FULLNAME
SEMAPHORE_LDAP_MAPPING_EMAIL