chore: rework plugin readmes, json changelogs and standalone repo setup

plugins/remote-desktop/CONTRIBUTING.md

@@ -0,0 +1,29 @@
+# Contributing to Remote Desktop
+
+## Development
+
+```bash
+npm run build      # build into dist/
+npm run test       # run this plugin's tests
+npm run typecheck  # type-check this plugin
+npm run validate   # check manifest.json
+npm run format     # format the code with Prettier
+```
+
+## Settings
+
+### Admin
+
+- **Enable Remote Desktop:** turn remote desktop on or off for everyone
+- **guacd URL:** where guacd runs, as `host:port`. Changes apply without a restart
+
+### Host
+
+- **RDP, VNC and Telnet:** turn each protocol on and set its port
+- **Display, audio, device and performance options:** values left alone follow the host defaults
+- **guacd settings:** use a different guacd for this host
+- **Remote desktop toolbar:** show the toolbar in the session
+
+## Permissions
+
+- `remote-desktop.sessions`: let session sharing and recording reach your remote desktop sessions. Admins and users have it by default.