chore(boilerplate): update git-setup.md with info about GPG keys fo…

…r signed git commits

#1

docs/contribute/git-setup.md

@@ -14,6 +14,52 @@ git config --local branch.autosetuprebase always
 git config --local merge.ff only
 ```
 
+## Configure signed git commits
+
+Assuming you have [Homebrew](https://brew.sh) installed:
+
+```shell
+git config --local commit.gpgsign true
+brew update
+brew upgrade
+brew uninstall gpg
+brew install gpg2
+git config --local gpg.program /usr/local/bin/gpg
+git config --local commit.gpgsign true
+```
+
+Then after gpg has been installed, create a key:
+
+```shell
+gpg --full-generate-key
+```
+
+Then show all keys:
+
+```shell
+gpg --list-keys
+```
+
+Then copy the long number of your key into the clipboard
+and register it as follows:
+
+```shell
+git config --local user.signingkey <Key from your list>
+```
+
+Then tell GitHub know what your key is by first exporting it
+(copy the output &mdash; with START and END line included &mdash; into the clipboard):
+
+```shell
+gpg --armor --export <Key from your list>
+```
+
+Then add this key to GitHub at GPG keys: <https://github.com/settings/keys>
+
+Your commits should now work and be signed.
+
+Check [GitHub docs](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits) for other options.
+
 ## References
 
 - [How to prevent merge conflicts](https://dev.to/github/how-to-prevent-merge-conflicts-or-at-least-have-less-of-them-109p)