doc: stack size in sequential/concurrent.
doc: stack size in sequential/concurrent.

	* doc/faq.tex (The server dies with ``stack exhaustion''): More,
	based on an answer given to Alexandre Gabus.

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