feat(anubis): add /healthz route to metrics server

Also add health check test for Docker Compose and update documentation
for health checking Anubis with Docker Compose.

Signed-off-by: Xe Iaso <me@xeiaso.net>

test/git-clone/docker-compose.yaml

@@ -12,11 +12,11 @@ services:
   anubis:
     image: ko.local/anubis
     environment:
-      BIND: ":3000"
+      BIND: ":8005"
       TARGET: http://cgit:80
       USE_REMOTE_ADDRESS: "true"
     ports:
-      - 3000:3000
+      - 8005:8005
 
 volumes:
   cgit-data:

test/git-clone/test.sh

@@ -21,6 +21,6 @@ docker compose up -d
 
 sleep 2
 
-(cd ./var/clones && git clone http://localhost:3000/status.git)
+(cd ./var/clones && git clone http://localhost:8005/status.git)
 
 docker compose down