add documentation for writing config files

Replace TODO introduced in commit 9c3c22 with documentation
explaining Git config API functions for writing configuration
files.

Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-push: fix link in man page

Signed-off-by: Tony Finch <dot@dotat.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'ta/doc-config'

* ta/doc-config:
  add documentation for writing config files
Merge branch 'tf/maint-doc-push'

* tf/maint-doc-push:
  git-push: fix link in man page
Git 2.1.0-rc1

Signed-off-by: Junio C Hamano <gitster@pobox.com>
RelNotes: no more check_ref_format micro-optimization

Signed-off-by: Junio C Hamano <gitster@pobox.com>
various contrib: Fix links in man pages

Inspired by 2147fa7e (2014-07-31 git-push: fix link in man page),
I grepped through the whole tree searching for 'gitlink:' occurrences.

Signed-off-by: Stefan Beller <stefanbeller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Release notes: grammatical fixes

Signed-off-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'mb/relnotes-2.1'

* mb/relnotes-2.1:
  Release notes: grammatical fixes
  RelNotes: no more check_ref_format micro-optimization
teach core.logallrefupdates an "always" mode

When core.logallrefupdates is true, we only create a new
reflog for refs that are under certain well-known
hierarchies. The reason is that we know that some
hierarchies (like refs/tags) do not typically change, and
that unknown hierarchies might not want reflogs at all
(e.g., a hypothetical refs/foo might be meant to change
often and drop old history immediately).

However, sometimes it is useful to override this decision
and simply log for all refs, because the safety and audit
trail is more important than the performance implications of
keeping the log around.

This patch introduces a new "always" mode for the
core.logallrefupdates option which will log updates to
everything under refs/, regardless where in the hierarchy it
is (we still will not log things like ORIG_HEAD and
FETCH_HEAD, which are known to be transient).