ring0: move docs to readme

kernel_module/README.adoc

@@ -16,6 +16,3 @@ Our kernel modules!
 .. link:strlen_overflow.c[]
 . Tracing
 .. link:kprobe_example.c[]
-. Arch
-.. x86
-... link:ring0.c[]

kernel_module/ring0.c

@@ -1,13 +1,4 @@
-/*
-This illustrates operations which are only possible in ring 0.
-https://stackoverflow.com/questions/7415515/how-to-access-the-control-registers-cr0-cr2-cr3-from-a-program-getting-segmenta/7419306#7419306
-
-It only works for x86_64.
-
-Then try to run this on userland and see the process be killed:
-
-    /ring0.out
-*/
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#ring0 */
 
 #include <linux/module.h>
 #include <linux/kernel.h>

kernel_module/user/ring0.c

@@ -1,8 +1,4 @@
-/*
-See ../ring0.c
-
-This executable is expected to segfault.
-*/
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#ring0 */
 
 #include <stdio.h>
 #include <stdlib.h>