doc: submodule.* config are keyed by submodule names
Ever since
941987a5 (git-submodule: give submodules proper names,
2007-06-11) introduced the ability to move a submodule from one path
to another inside its superproject tree without losing its identity,
we should have consistently used submodule.<name>.* to access
settings related to the named submodule.
Reported-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: W. Trevor King <wking@tremily.us>
Signed-off-by: Junio C Hamano <gitster@pobox.com>