docs: document plugin seeding usage

README.md

@@ -33,6 +33,13 @@ This repository contains a hardened Docker Compose stack for the DigitechFlow Wo
 - Local data directories (`db_data/`, `wordpress_data/`, `redis_data/`) plus `wp-config.php` are gitignored to prevent leaking content/secrets.
 - `config/plugins.txt` lists plugin slugs to auto-install. Add one per line and rerun `docker compose up wpcli_seed`.
 
+### Managing the plugin seed list
+`config/plugins.txt` is a newline-delimited list of plugin slugs (directory names from wordpress.org). To ensure a plugin is installed and active whenever this stack boots:
+
+1. Add the slug to the file, e.g. `wordpress-seo`.
+2. Run `docker compose up wpcli_seed`. The one-shot `wordpress:cli` container will wait for WordPress to be ready, install any missing plugins from the list, and activate them.
+3. Repeat whenever you add/remove required plugins. Existing installations are left untouched unless they match entries in the file (in which case they’re only ensured active).
+
 ## Operations
 - Update images: `docker compose pull && docker compose up -d`.
 - View logs: `docker compose logs -f <service>`.