List branches deployed in an Actions summary

[Tom-van-Woudenberg]

Expected format of the summary as follows

---

Branch 🎋	Link 🔗
feat/10/stuff	username.github.io/reponame/feat-10-stuff

Primary branch publish is at:

• username.github.io/reponame/
• and username.github.io/reponame/publish

Aliases:

• stuff -> feat-10-stuff

---

Possible follow-up: display success/failure per branch in the summary as well

Refs:

• https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#adding-a-job-summary
• https://github.blog/2022-05-09-supercharging-github-actions-with-job-summaries/