repo-settings: rename the traditional default fetch.negotiationAlgorithm
Give the traditional default fetch.negotiationAlgorithm the name
'consecutive'. Also allow a choice of 'default' to have Git decide
between the choices (currently, picking 'skipping' if
feature.experimental is true and 'consecutive' otherwise). Update the
documentation accordingly.
Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>