Fix the installation target to make sure that the manual is

installed in the correct location.

PR:	8851
Submitted by:	Yoshifumi Hiramatsu <hiramatu@boreas.dti.ne.jp>
                and Gomez Henri <hgomez@slib.fr>


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@92164 13f79535-47bb-0310-9956-ffa450edef68