[Improvement] Document metadata to be persisted for adaptive scheduling

### What would you like to be improved?

https://stormcrawler.apache.org/docs/latest/index.html#_adaptivescheduler

### How should we improve?

These need to be in the config under _  metadata.persist_

```
   - signature
   - fetchInterval
   - signatureChangeDate
   - Last-Modified
   - protocol.etag
```
