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

plugins/docker/CONTRIBUTING.md

@@ -0,0 +1,22 @@
+# Contributing to Docker
+
+## 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
+
+### Host
+
+- **Enable Docker:** show the Docker tab for this host
+- **Container Runtime:** Docker or Podman
+
+## Permissions
+
+- `docker.use`: open the Docker manager and container consoles on hosts with Docker turned on. Admins and users have it by default.