Many people filing issues that turn into proposals have no idea what that means.
The proposal process is linked from the code contribution guidelines, but reading those is not necessary to file an issue.
And because the issue template targets bug fixes, adding more to the issue template is not appropriate either.
It would be nice for gopherbot to post a link to the proposal process when an issue
becomes a proposal.

Separately, it would also be nice if there were a clear place for information about the status of a proposal.
GitHub being what it is, with no pinned comments or anything like that, the only place you can put that information and be sure it will be displayed is in the issue description (the top-most comment box).

So probably what gopherbot should do instead of leaving a comment is to insert and then maintain a basic header at the top of the issue description that clearly states the status of the issue and where it is in the proposal process, along with a link to the proposal process description itself.

To start, it would be enough to insert the header with a link to the proposal process doc.