Added docs about manually triggering alpine mirro syncs

Author: dysen

deploy/alpine-mirror/README.md

@@ -3,4 +3,11 @@
 - Adjust ./synchroniser/crontab for desired schedule of synchronising
 - Adjust ./synchroniser/mirror.sh for which repos to exclude, etc.
 - Image has to be re-built whenever crontab or mirror.sh are changed
-- Run by `podman compose up` or `docker compose up`
+- Run by `podman compose up` or `docker compose up`
+
+# Notes
+
+- [Alpine Wiki - How to setup a Mirror](https://wiki.alpinelinux.org/wiki/How_to_setup_a_Alpine_Linux_mirror)
+- You can trigger the syncs manually via
+  - Podman - `podman exec -it alpine-mirror-sync /app/mirror.sh`
+  - Docker - `docker exec -it alpine-mirror-sync /app/mirror.sh`