Building xmlstarlet-1.4.0 on OS X 10.6, 'make install' is placing the documentation files directly in PREFIX/share/doc rather than in PREFIX/share/doc/xmlstarlet. The latter (subdir) appears to be the intended location, since Makefile has:
docdir = ${datarootdir}/doc/${PACKAGE_TARNAME}
but PACKAGE_TARNAME is not defined anywhere in Makefile. That's because configure.ac has:
AM_SUBST_NOTMAKE(PACKAGE_TARNAME)
Those two together (docdir defined in terms of PACKAGE_TARNAME in the makefile but PACKAGE_TARNAME excluded from being defined in the makefile) mean docdir is not set correctly. I tried to diagnose further, but actually can't find where PACKAGE_TARNAME or docdir are defined originally (they appear in the configure script but not in its templates or distributed .m4).
Somehow I didn't realize automake would use those variables, seems like this has been broken for a while except that the docs weren't being installed up until now, oops.
PACKAGE_TARNAME is defined by AC_INIT[1]. docdir is defined by automake, the automake manual actually says it uses PACKAGE[2].
[1] http://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Initializing-configure.html
[2] http://www.gnu.org/software/automake/manual/html_node/Standard-Directory-Variables.html
Fixed in release 1.4.1