doc: avoid ambiguous rules.
doc: avoid ambiguous rules.

	* doc/trajectories/local.mk: here.
	http://lists.gnu.org/archive/html/bug-make/2011-05/msg00001.html

aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi