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

plugins/acme-ssl/CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# Contributing to ACME Certificates
+
+## 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
+
+- **Renew automatically:** checks twice a day and renews when there is no certificate, it is self-signed, it does not cover the domain, or it expires within 30 days
+- **Domain:** the public domain name the certificate covers
+- **Email:** the contact email for the ACME account
+- **Certificate authority:** Let's Encrypt, Let's Encrypt staging, or a custom ACME directory
+- **ACME directory URL:** only for a custom authority, and must be https
+- **Challenge type:** HTTP or DNS (Cloudflare)
+- **Cloudflare API token:** used by the DNS challenge, stored encrypted
+
+## Permissions
+
+- `acme-ssl.manage`: see the certificate status and request a new certificate. Only admins have it by default.