Put HTML documentation in proper directory.
Patch by Chris Mayo, https://bugs.gentoo.org/show_bug.cgi?id=296112
--- doc/Makefile.am.orig
+++ doc/Makefile.am
@@ -182,8 +182,6 @@
# Install (automake)
#
-htmldir = $(datadir)/doc/docbook2X
-
man_MANS = $(MAN_FILES)
html_DATA = $(HTML_FILES)
info_TEXINFOS = docbook2X.texi