Fix build requirement software name.

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@1549 e5f2f494-b856-4b98-b285-d166d9295462

doc/userguide/userguide.xml

@@ -401,7 +401,7 @@ var/
           <para>
             When using source code retrieved via Subversion additional
             software will be required:  automake (v1.11 or newer),
-            libtoolize, and autoconfigure (2.59 or newer).
+            libtoolize, and autoconf (2.59 or newer).
             These may need to be installed.
           </para>
         </note>