docs(docker,delegation): Fix .well-known docs - check below for details

.well-known env var in example composes now point to `example.com:443`,
and are turned on by default for Caddy labels and the Traefik configs.
For the Caddyfile example, they're left uncommented. Added small
bulletpoint on how to use this env var. Consistencize all the
.well-known comments inside these composes.

I don't want to overly fix the example composes and get it wrong, so
this small change should be enough. Split-domain deployments are fully
outsourced to the Delegation page now, and some changes are also made
there to be more comprehensive.

docs/advanced/delegation.mdx

@@ -24,6 +24,7 @@ client = "https://matrix.example.com"
 server = "matrix.example.com:443"
 
 # (optional) customize your support contacts
+# Defaults to members of #admin room if unset
 #support_page =
 #support_role = "m.role.admin"
 #support_email =
@@ -42,6 +43,10 @@ services:
         client=https://matrix.example.com,
         server=matrix.example.com:443
         }
+
+      # You can also configure individual .well-knowns as below
+      # CONTINUWUITY_WELL_KNOWN__CLIENT: https://matrix.example.com
+      # CONTINUWUITY_WELL_KNOWN__SERVER: matrix.example.com:443
 ```
 
 ## Serving with a reverse proxy