Documentation/Changes: perl is needed to build the kernel

Perl is used on the kernel Makefile to generate documentation, firmwares
in c source form, sources, graphs, and some headers and this fact is
undocumented.

[akpm@linux-foundation.org: 80-columns, please]
Signed-off-by: Jose Luis Perez Diez <jluis@escomposlinux.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/Changes b/Documentation/Changes
index 6643924..6d0f1ef 100644
--- a/Documentation/Changes
+++ b/Documentation/Changes
@@ -72,6 +72,13 @@
 your kernel.  This change does, however, mean that you need a recent
 release of binutils.
 
+Perl
+----
+
+You will need perl 5 and the following modules: Getopt::Long, Getopt::Std,
+File::Basename, and File::Find to build the kernel.
+
+
 System utilities
 ================