docs: update known kernel bugs list

"Storm of softlockups" starts with a simple BUG_ON, but after the
BUG_ON, all cores that are waiting on spinlocks get stuck.
The _first_ kernel call trace is required to identify the bug.
At least two such bugs have been identified.

Add some notes about the conflict between LOGICAL_INO and balance,
and the recently added bees workaround.

Update the gotchas page for balances to point to the kernel bugs page.
Remove "bees and the full balance will both work correctly" as that
statement is not true.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

docs/gotchas.md

@@ -122,6 +122,10 @@ shutdown time at the cost of increased startup time.
 Balances
 --------
 
+First, read [`LOGICAL_INO` and btrfs balance WARNING](btrfs-kernel.md).
+bees will suspend operations during a btrfs balance to work around
+kernel bugs.
+
 A btrfs balance relocates data on disk by making a new copy of the
 data, replacing all references to the old data with references to the
 new copy, and deleting the old copy.  To bees, this is the same as any
@@ -149,9 +153,7 @@ taking into account the extra work bees has to do.
 If the filesystem must undergo a full balance (e.g. because disks were
 added or removed, or to change RAID profiles), then every data block on
 the filesystem will be relocated to a new address, which invalidates all
-the data in the bees hash table at once.  bees and the full balance will
-both work correctly if they are both allowed to run at the same time,
-but it is quite slow.  In such cases it is a good idea to:
+the data in the bees hash table at once.  In such cases it is a good idea to:
 
   1.  Stop bees before the full balance starts,
   2.  Wipe the `$BEESHOME` directory (or delete and recreate `beeshash.dat`),