Redirect sign and verify git tag aliases

The 'stag' and 'vtag' git aliases are mentioned in both the Split GPG
and the Code signing documents. Consolidated into the Code signing
document.

The Code signing version was kept as it explicitly calls the Bash shell.

user/security-in-qubes/split-gpg.md

@@ -262,16 +262,7 @@ If you would like to automatically sign all commits, you can add the following s
 	gpgSign = true
 ```
 
-Lastly, if you would like to add aliases to sign and verify tags using the conventions the Qubes OS Project recommends, you can add the following snippet to `~/.gitconfig`.
-
-```
-[alias]
-stag = "!id=`git rev-parse --verify HEAD`; git tag -s user_${id:0:8} -m \"Tag for commit $id\""
-vtag = !git tag -v `git describe`
-```
-
-Replace `user` with your short, unique nickname.
-Now you can use `git stag` to add a signed tag to a commit and `git vtag` to verify the most recent tag that is reachable from a commit.
+Lastly, if you would like to add aliases to sign and verify tags using the conventions the Qubes OS Project recommends, refer to the [code signing documentation](/doc/code-signing/#using-pgp-with-git).
 
 ## Importing public keys