feat(syslog): set-up help on the page, port 5514 published, Docker-hidden senders called out (#6003)

The Syslog page says where to send (this server, its port and protocols) and
where the setting is on Synology, QNAP, TrueNAS, OpenWrt, UniFi and rsyslog,
open until a device sends. A sender whose address is on Steward's own
container network (Swarm ingress publishing hides the real sender) is
flagged, with the host-mode ports to publish instead. compose files and the
Dockerfile publish 5514/udp and /tcp; docs/plugins/syslog.md describes the
plugin and the deploy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

compose.deploy.yml

@@ -16,6 +16,13 @@ services:
     pull_policy: always
     ports:
       - "5000:5000"
+      # Syslog (plugins/syslog): devices send here. Steward runs unprivileged,
+      # so it listens above 1024; publish 514 to it instead ("514:5514/udp")
+      # if a device can't choose its port. Under Docker Swarm use the long form
+      # with `mode: host`: Swarm's default ingress publishing hands every packet
+      # over from one internal address, and devices are told apart by theirs.
+      - "5514:5514/udp"
+      - "5514:5514/tcp"
     networks:
       - backend
     volumes: