docs: add Related section linking sibling repos

mysql/README.md

@@ -1,2 +1,13 @@
 # mysql-keepalive
 Go utility performs periodic operations to MySQL server.
+
+## Related
+
+Part of the `*-keepalive` family — same pattern, different databases:
+
+- [mongodb-keepalive](https://github.com/tiennm99/mongodb-keepalive) — Mongodb
+- [redis-keepalive](https://github.com/tiennm99/redis-keepalive) — Redis
+- [postgresql-keepalive](https://github.com/tiennm99/postgresql-keepalive) — Postgresql
+- [valkey-keepalive](https://github.com/tiennm99/valkey-keepalive) — Valkey
+- [couchbase-keepalive](https://github.com/tiennm99/couchbase-keepalive) — Couchbase
+