gitHub* template functions return data from the GitHub API.
By default, chezmoi makes anonymous GitHub API requests, which are subject to
(currently 60 requests per hour per source IP address). chezmoi caches results
from identical GitHub API requests for the period defined in
gitHub.refreshPeriod (default one minute).
If any of the environment variables
$GITHUB_TOKEN are found, then the first one found
will be used to authenticate the GitHub API requests which have a higher rate
limit (currently 5,000 requests per hour per user).
In practice, GitHub API rate limits are high enough chezmoi's caching of results mean that you should rarely need to set a token, unless you are sharing a source IP address with many other GitHub users. If needed, the GitHub documentation describes how to create a personal access token.