docs: clarify separation of multiplayer and sysadmin plugins

- Updated documentation to emphasize the distinct functionalities of `FFM.Plugin.Multiplayer` (networking/sync) and `FFM.Plugin.Sysadmin` (UI modernization/settings).
- Enhanced descriptions in relevant files to prevent confusion between the two plugins and their purposes.
- Added notes in the multiplayer hub to clearly state that sysadmin and web UI features are separate topics.

This commit improves clarity in the documentation regarding plugin functionalities.

docs/topics/multiplayer-and-networking/overview.md

@@ -1,12 +1,15 @@
 ---
 title: Multiplayer & networking
 sidebar_label: Multiplayer & networking (hub)
-description: P2P roadmap, Web UI bridge, multiplayer plugin — entry points.
+description: P2P roadmap and multiplayer plugin — separate from Sysadmin / Web UI.
 ---
 
 # Multiplayer & networking
 
+This hub covers **networking and multiplayer** only. It does **not** include [FFM.Plugin.Sysadmin](/wiki/plugins/ffm-plugin-sysadmin) (UI settings / modernizer) or [FFM.Plugin.WebUIBridge](/wiki/plugins/ffm-plugin-web-ui-bridge) (DC2 web UI) — those are separate plugins.
+
 - Wiki: [FFM.Plugin.Multiplayer](/wiki/plugins/ffm-plugin-multiplayer)
 - Release: [FFM.Plugin.Multiplayer release](/wiki/releases/plugins/ffm-plugin-multiplayer-release)
 - Imported: [Steamworks P2P multiplayer roadmap](/wiki/legacy/wiki-import/Steamworks-P2P-Multiplayer-Roadmap)
-- Imported: [Web UI bridge](/wiki/legacy/wiki-import/Web-UI-Bridge)
+
+**Related (separate topic):** [Web UI bridge](/wiki/legacy/wiki-import/Web-UI-Bridge) — documentation import for browser-based UI; not part of the multiplayer stack.