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

plugins/ldap/CONTRIBUTING.md

@@ -0,0 +1,21 @@
+# Contributing to LDAP
+
+## 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
+
+- **Directories:** the LDAP servers people can sign in with. Each has a display name, host and port, TLS, bind DN and password, user and group search settings, an admin group and an allowed users list. The bind password is stored encrypted
+
+## Permissions
+
+- `ldap.manage`: add, edit and remove LDAP directories. Only admins have it by default.