Allows optionally signing the commits that git subtree creates. This can
be necessary when working in a repository that requires gpg signed
commits.
Signed-off-by: Patrik Weiskircher <patrik@pspdfkit.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The .txt extensions were changed to .adoc in 1f010d6bdf (doc: use .adoc
extension for AsciiDoc files, 2025-01-20).
Do the same for contrib/subtree.
Signed-off-by: Todd Zullinger <tmz@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>