Fix misspellings collected by members of KJ list.

Fix the misspellings of "propogate", "writting" and (oh, the shame
:-) "kenrel" in the source tree.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 5922e84..d3d3c25 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -228,7 +228,7 @@
 
 pid_max:
 
-PID allocation wrap value.  When the kenrel's next PID value
+PID allocation wrap value.  When the kernel's next PID value
 reaches this value, it wraps back to a minimum PID value.
 PIDs of value pid_max or larger are not allocated.