Update README.md

SamyPesse · SamyPesse · commit f1aed4b68680 · 2015-05-02T14:13:35.000+02:00
diff --git a/chapter9/README.md b/chapter9/README.md
@@ -1,6 +1,6 @@
 # Memory management: physical and virtual
 
-The kernel knows the size of the physical memory available thanks to [Grub](../Chapter-3/README.md).
+The kernel knows the size of the physical memory available thanks to [GRUB](../Chapter-3/README.md).
 
 In our implementation, the first 8 megabytes of physical memory will be reserved for use by the kernel and will contain:
 
