Design Better CRDs

* Current CRDs

```yaml
apiVersion: sentinelfs.io/v2
kind: FileMonitoringPolicy
metadata:
  name: monitor
spec:
  podSelector:
    labels:
      - key: app
        value: pipeline
  files:
    - path: /app/*
    - path: /etc/secrets/*
```

* There is a need for better one so that data can be appended conveniently 