README.md: add further reading, Andrew Ayer: It's Now Possible To Sign Arbitrary Data With Your SSH Keys

It already happened 🎉

README.md

@@ -7,15 +7,43 @@ which does about the same for PGP.
 
 ## Where to find keys
 
-* GitHub, Giteas and GitLabs expose user public keys when you append a .keys after their profile page
-* Good ideas are made to be copied, so maybe there will be more repositories like this ;)
+* GitHub, Giteas and GitLabs expose user public keys (without useful names)
+  when you append a `.keys` after their profile page
+  * For example: https://github.com/Mikaela.keys https://gitea.blesmrt.net/Mikaela.keys https://gitlab.com/Mikaela.keys
+* Good ideas are made to be copied, so maybe there will be more repositories like this :wink:
+
+## Quick howto
+
+I don't mean this to be used directly, only to be took inspiration from. See the first
+link in further reading.
+
+```bash
+mkdir -p ~/src/gitea.blesmrt.net/Mikaela
+cd ~/src/gitea.blesmrt.net/Mikaela
+git clone https://gitea.blesmrt.net/Mikaela/ssh-allowed_signers.git
+git config --global gpg.ssh.allowedSignersFile ~/src/gitea.blesmrt.net/Mikaela/ssh-allowed_signers/allowed_signers
+```
+
+Git commands should now recognised commits signed with keys I have allowed.
+In the last command it's fine to remove `--global` to only affect the single
+repository you are on (while I haven't tested this), should that repository
+be something only I am signing in or something I need to verify otherwise
+enough to list it here.
+
+On the last command, `git config` turns it into absolute path, while manually
+edited `.gitconfig` can literally have the above. I wonder if the command
+would understand `--` before the file, but not enough to actually try it :smiley:
 
 ## Further reading
 
-* [Caleb Hearth: Signing Git Commits with Your SSH Key](https://calebhearth.com/sign-git-with-ssh), [web.archive.org](https://web.archive.org/web/20211117182628/https://calebhearth.com/sign-git-with-ssh), inspired me to try this
-* [GitHub feedback: Allow using SSH keys to sign commits](https://github.com/github/feedback/discussions/7744)
-  * TODO: notify here when it actually works, link to their guide or maybe remove the section?
+* [Caleb Hearth: Signing Git Commits with Your SSH Key](https://calebhearth.com/sign-git-with-ssh) ([web.archive.org](https://web.archive.org/web/20211117182628/https://calebhearth.com/sign-git-with-ssh)) inspired me to try this
+* [Andrew Ayer: It's Now Possible To Sign Arbitrary Data With Your SSH Keys](https://www.agwa.name/blog/post/ssh_signatures) instructs on signing and verifying files outside of git
+
+### Forge support
+
 * [Merged Gitea PR for add support for ssh commit signing](https://github.com/go-gitea/gitea/pull/17743)
   * TODO: link to their blog once it's released
-* [Fedora update request for git](https://bugzilla.redhat.com/show_bug.cgi?id=2029604)
-  * TODO: remove this mention when it happens? It does have the test instructions I took
+* [GitHub feedback: Allow using SSH keys to sign commits](https://github.com/github/feedback/discussions/7744)
+  * TODO: notify here when it actually works, link to their guide or maybe remove the section?
+* [GitLab issues: Support for SSH signed commits](https://gitlab.com/gitlab-org/gitlab/-/issues/343879)
+  * TODO: a better link when this happens