Retrospective commit signing guide

Retrospective commit signing guide
- Signing previously pushed commits
  - Steps

Signing previously pushed commits

If you have pushed a commit without signing this can result in your PR not being able to be merged into the main or default branch. The following steps will guide you through retrospectively signing your commits. Note you can sign multiple commits if required.

Please take the time to understand the commands that you are using, this is just a guide.

Steps

Identify unsigned commits
You have a branch that contains one or more unsigned commits. In the screenshot below, there are two unsigned commits followed by two commits showing the Verified label, which indicates they were signed.
Understand the issue
The first two commits aren't verified, and therefore the merge to the main branch is not allowed:
Switch to the branch with unsigned commits
Go to your CLI and ensure that you are on the branch with the unsigned commits.
Start an interactive rebase
Issue the following command:
```
git rebase -i --root
```
This puts the editor into interactive mode for rebase. You will see the commit history as shown in the screenshot below:
Mark commits for editing
Scroll down the list until you find the commits you want to sign. Change the keyword pick to edit for those commits.

If you are using Nano, save the changes with Ctrl+X and confirm with Enter. For Vi, exit with :wq to save and quit.
Amend the commit to include a signature
For each commit you flagged as edit, run the following commands:
```
git commit -S --amend --no-edit
git rebase --continue
```
Rebase will cycle through the commits you flagged for editing:

Repeat the amend and continue steps for each commit.
Complete the rebase
Once rebasing is complete, you will see a message like:
```
Successfully rebased and updated refs/heads/…
```
Push the changes
Push the updated commits back to your branch. Use a force push if necessary:
```
git push -f
```
Verify the changes
Refresh the browser window for your PR. You should now see the verified commits: