Fix: use static IP for mailman-core and update documentation

- Assign static IP 172.29.199.10 to mailman-core to ensure host Postfix can reach LMTP.
- Update MM_HOSTNAME and mailman-extra.cfg to use the static IP.
- Update README.md with correct networking recommendations for host-based MTAs.
- Add missing configuration files to repository.

config/cron.d/mailman_logrotate

@@ -0,0 +1,9 @@
+/var/log/mailman-core/*.log /var/log/mailman-web/*.log {
+    daily
+    rotate 7
+    compress
+    delaycompress
+    notifempty
+    missingok
+    create 0640 root adm
+}