update to "KNOWN BUGS"

KNOWN_BUGS.txt:
  update

KNOWN_BUGS.txt

 This file should contain all know fatal bugs in the Maria storage
 engine for the last source or binary release.  Minor bugs, extensions
 and feature request and bugs found since this release can be find in the
-MySQL bugs databases at: http://bugs.mysql.com/
+MySQL bugs databases at: http://bugs.mysql.com/ (category "Maria
+storage engine").
 
 There shouldn't normally be any bugs that affects normal operations in
 any Maria release.  Still, there are always exceptions and edge cases
@@ -37,9 +38,9 @@ Known bugs that we are working on and will be fixed shortly
 - LOAD INDEX commands are for the moment ignored for Maria tables
   (The code needs to be rewritten to do all reads through page cache to
   avoid half-block reads)
-- Freeing maria tmp table after fetching rows using prepared statements causes
-  a crash.
-
+- Some concurrency bugs in Maria's page cache which sometimes show up
+  under load http://bugs.mysql.com/bug.php?id=34161 and
+  http://bugs.mysql.com/bug.php?id=34634 .
 
 Known bugs that are planned to be fixed before Beta
 ===================================================