URL change for submitting kernel patches

Mr. Torvalds changed where the how to doc was located for
submitting kernel changes.

Change-Id: I3125e840caa3b081b39ad622ff962b98f1abcd0d
Signed-off-by: Chris Austen <austenc@us.ibm.com>
diff --git a/contributing.md b/contributing.md
index 7837a43..d161d7a 100644
--- a/contributing.md
+++ b/contributing.md
@@ -57,7 +57,7 @@
 
 For C code, we typically use the Linux coding style, which is documented at:
 
-  http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/CodingStyle
+  http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst
 
 In short: