docs: Update all docker-compose files to use the same version and examples (#2159)

Initial pass for achieving more consistency with docker-compose related configs.

* Set DMS_DEBUG to 0
* align with default docker-compose.yml

Co-authored-by: Casper <casperklein@users.noreply.github.com>
Co-authored-by: Georg Lauterbach <44545919+georglauterbach@users.noreply.github.com>
Co-authored-by: Brennan Kinney <5098581+polarathene@users.noreply.github.com>

docker-compose.yml

@@ -3,8 +3,8 @@ version: '3.8'
 services:
   mailserver:
     image: docker.io/mailserver/docker-mailserver:latest
-    hostname: <HOSTNAME> # <-- CHANGE THIS
-    domainname: <DOMAINNAME> # <-- CHANGE THIS
+    hostname: mail
+    domainname: example.com
     container_name: mailserver
     env_file: mailserver.env
     # To avoid conflicts with yaml base-60 float, DO NOT remove the quotation marks.
@@ -24,4 +24,7 @@ services:
       - ./config/:/tmp/docker-mailserver/
     restart: always
     stop_grace_period: 1m
-    cap_add: [ "NET_ADMIN", "SYS_PTRACE" ]
+    cap_add:
+      - NET_ADMIN
+      - SYS_PTRACE
+