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
fsck: check "tagger" lines

The fsck_tag function does not check very much about tags at
all; it just makes sure that we were able to load the
pointed-to object during the parse_tag phase. This does
check some basic things (the "object" line is OK, and the
pointed-to object exists with the expected type).

We did not, however, check the "tagger" line at all; if they
exist, we should feed them to fsck_ident (and it is OK if
they do not, as early versions of git did not include them).

This patch runs through the whole tag object during
fsck_tag, similar to what we do in fsck_commit. Some of
these checks are technically redundant with just checking
that parse_tag filled in the "tag->tagged" field. However:

  1. We have to parse through those lines anyway to get to
     the tagger line, so we need to sanity check our
     parsing.

  2. We can give more specific errors (e.g., report a
     malformed "object" line).

  3. Previously we depended on implementation details of
     parse_tag for our fsck (e.g., that it would never fill
     in "tagged" if the types did not match). Now our
     exhaustive checks are in one place, which makes it
     easier to verify exactly what fsck is checking.