added config to manage keep for every cron

README.md

@@ -19,6 +19,19 @@ Originally adapted from https://github.com/zfsonlinux/zfs-auto-snapshot
 make install
 ```
 
+## Configuration
+Snapshot retention limits can be configured in `zfs-auto-snapshot.conf`:
+- `KEEP_FREQUENT`: snapshots rotated every 15 minutes (default: `4`)
+- `KEEP_HOURLY`: hourly snapshots (default: `24`)
+- `KEEP_DAILY`: daily snapshots (default: `31`)
+- `KEEP_WEEKLY`: weekly snapshots (default: `12`)
+- `KEEP_MONTHLY`: monthly snapshots (default: `12`)
+
+To apply configuration changes and update installed cron files, run:
+```sh
+make install
+```
+
 ## Uninstallation
 ```sh
 make uninstall