doc: use .adoc extension for AsciiDoc files

We presently use the ".txt" extension for our AsciiDoc files.  While not
wrong, most editors do not associate this extension with AsciiDoc,
meaning that contributors don't get automatic editor functionality that
could be useful, such as syntax highlighting and prose linting.

It is much more common to use the ".adoc" extension for AsciiDoc files,
since this helps editors automatically detect files and also allows
various forges to provide rich (HTML-like) rendering.  Let's do that
here, renaming all of the files and updating the includes where
relevant.  Adjust the various build scripts and makefiles to use the new
extension as well.

Note that this should not result in any user-visible changes to the
documentation.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/Documentation/git-refs.adoc b/Documentation/git-refs.adoc
new file mode 100644
index 0000000000..95f25776aa
--- /dev/null
+++ b/Documentation/git-refs.adoc
@@ -0,0 +1,72 @@
+git-refs(1)
+===========
+
+NAME
+----
+git-refs - Low-level access to refs
+
+
+SYNOPSIS
+--------
+[verse]
+'git refs migrate' --ref-format=<format> [--dry-run]
+'git refs verify' [--strict] [--verbose]
+
+DESCRIPTION
+-----------
+
+This command provides low-level access to refs.
+
+COMMANDS
+--------
+
+migrate::
+	Migrate ref store between different formats.
+
+verify::
+	Verify reference database consistency.
+
+OPTIONS
+-------
+
+The following options are specific to 'git refs migrate':
+
+--ref-format=<format>::
+	The ref format to migrate the ref store to. Can be one of:
++
+include::ref-storage-format.adoc[]
+
+--dry-run::
+	Perform the migration, but do not modify the repository. The migrated
+	refs will be written into a separate directory that can be inspected
+	separately. The name of the directory will be reported on stdout. This
+	can be used to double check that the migration works as expected before
+	performing the actual migration.
+
+The following options are specific to 'git refs verify':
+
+--strict::
+	Enable stricter error checking. This will cause warnings to be
+	reported as errors. See linkgit:git-fsck[1].
+
+--verbose::
+	When verifying the reference database consistency, be chatty.
+
+KNOWN LIMITATIONS
+-----------------
+
+The ref format migration has several known limitations in its current form:
+
+* It is not possible to migrate repositories that have worktrees.
+
+* There is no way to block concurrent writes to the repository during an
+  ongoing migration. Concurrent writes can lead to an inconsistent migrated
+  state. Users are expected to block writes on a higher level. If your
+  repository is registered for scheduled maintenance, it is recommended to
+  unregister it first with git-maintenance(1).
+
+These limitations may eventually be lifted.
+
+GIT
+---
+Part of the linkgit:git[1] suite