Update 6.12.0.md

Update the changelog to include a callout about particular ZFS pools, after https://forums.unraid.net/topic/141059-lost-14tb-zfs-pool-after-612/

docs/unraid-os/release-notes/6.12.0.md

@@ -101,7 +101,19 @@ created with the same 'profile' as the existing vdevs. Additional flexibility in
 Pools created with the **steini84** plugin can be imported as follows: First create a new pool with the number
 of slots corresponding to the number of devices in the pool to be imported. Next assign all the devices to
 the new pool.  Upon array Start the pool should be recognized, though certain zpool topologies may not be
-recognized (please report).
+recognized (please report). Please note that only pools using partition #1 can be imported in this release, e.g. this `lsblk` output:
+
+```
+# lsblk
+NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
+sdb           8:16   0   7.3T  0 disk
+├─sdb1        8:17   0     2G  0 part
+└─sdb2        8:18   0   7.3T  0 part
+```
+
+indicates that the second (`sdb2`) partition of the disk is being used for data, and **cannot** be imported. You can continue to use
+the pool by importing it manually post-upgrade (after every boot), but it will not be visible in the UI. You can configure automatic import on boot
+by adding `zpool import <poolname>` to your `/boot/config/go` file.
 
 Mixed topologies are not supported.  For example, a pool with both a mirror root vdev and a raidz root vdev is not
 recognized.