Trackers are public and readable by anyone. To edit or create trackers, paste a
fine-grained Personal Access Token
with Gists → Read and write permission.
The token is stored in localStorage so you only need to paste it once per browser.
This creates a new tracker entry inside the single shared Gist file: simple-habit-tracker-data.json.
Your tracker was added to the shared Gist file. Because the page reads everything from the single Gist,
you do not need to update index.html anymore.