docs: Minor FEL root clarifications

docs/_pages/installation/roborock.md

@@ -250,6 +250,9 @@ dd if=/dev/nandb | gzip > /tmp/nandb.img.gz
 dd if=/dev/nandk | gzip > /tmp/nandk.img.gz
 ```
 
+These two flash partitions contain the factory calibration and identity data which is unique for each robot and can't
+be recovered without a backup if data loss should ever occur.
+
 Disconnect or open a second terminal and pull those backups to your laptop via `scp` and store them in a safe place:
 ```
 scp -O -i ./your_keyfile [email protected]:/tmp/nand* .
@@ -312,4 +315,4 @@ For that, just browse to `http://192.168.8.1`.
 
 After reassembling the robot you can continue with the <a href="https://valetudo.cloud/pages/general/getting-started.html#using-valetudo">getting started guide</a>.
 
-</div>
+</div>