Documentation/config: mention "now" and "never" for 'expire' settings
Documentation/config: mention "now" and "never" for 'expire' settings

In addition to approxidate-style values ("2.months.ago", "yesterday"),
consumers of 'gc.*expire*' configuration variables also accept and
respect 'now' ("do it immediately") and 'never' ("suppress entirely").

Suggested-by: Michael Haggerty <c24c152f145c57791e809b126db9e61bd1c1782d@alum.mit.edu>
Signed-off-by: Eric Sunshine <8d6e34f987851aa599257d3831a1af040886842f@sunshineco.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git