Previously, we used the `hotlist: community-help` label to mark issues
that were good candidates for contributions from the community.
Recently, we also started using the `good first issue` label to mark
issues that would additionally be suitable for first-time contributors.
This commit is part of the work to replace `hotlist: community-help`
with the newly added `help wanted` label, which (same as
`good first issue`) is a [default GitHub label][1]. This commit changes
all occurrences of `hotlist: community-help` in the documentation to
`help wanted` and also documents the purpose of the `help wanted` and
`good first issue` labels.
[1]: https://docs.github.com/en/github/managing-your-work-on-github/managing-labels#about-default-labels
PR Close#41195