Documentation/kprobes: add s390 to list of supported architectures

s390 supports kprobes since 2006 but is missing in the list of
architectures that support kprobes.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index 4bbeca8..4227ec2 100644
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -300,6 +300,7 @@
 - arm
 - ppc
 - mips
+- s390
 
 3. Configuring Kprobes