Documentation: change email address for Hans Koch

My old mail address doesn't exist anymore. This changes all occurrences
to my new address.

Signed-off-by: Hans J. Koch <hjk@hansjkoch.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>