Re: [PATCH v3] signature-format.txt: note SSH and X.509 signature delimiters

> This document only explains PGP signatures, but Git now supports X.509
> signatures as of 1e7adb9756 (gpg-interface: introduce new signature
> format "x509" using gpgsm, 2018-07-17), and SSH signatures as of
> 29b315778e (ssh signing: add ssh key format and signing code,
> 2021-09-10).
>
> Additionally, explain that these signature formats are controlled
> `gpg.format`, linking to its documentation, and explain in said
> `gpg.format` documentation that the underlying signature format is
> documented in signature-format.txt.
>
> Signed-off-by: Gwyneth Morgan <gwymor@tilde.club>
> ---
>  Documentation/config/gpg.txt          |  3 +++
>  Documentation/gitformat-signature.txt | 22 +++++++++++++++++-----
>  2 files changed, 20 insertions(+), 5 deletions(-)