typos: s/ducument/document/

s/ducument/document/

Signed-off-by: Adrian Bunk <bunk@stusta.de>

Documentation/DocBook/Makefile

@@ -2,7 +2,7 @@
 # This makefile is used to generate the kernel documentation,
 # primarily based on in-line comments in various source files.
 # See Documentation/kernel-doc-nano-HOWTO.txt for instruction in how
-# to ducument the SRC - and how to read it.
+# to document the SRC - and how to read it.
 # To add a new book the only step required is to add the book to the
 # list of DOCBOOKS.