Add pull request template

[rkoeze]

Adds a PR template to encourage standard descriptions as discussed in #4912 (comment).

[tomhughes]

Does that template really address the things @gravitystorm was talking about? It doesn't seem like it does to me but then I'm not sure a PR template can which is why I was a bit confused by the suggestion - the automation he was suggesting seems more likely to work.

I'm certainly not convinced that asking people to assess the risk of a change is going to be useful - risk of what exactly? If somebody truly thought a change was risky then they shouldn't really be proposing it!

[rkoeze]

Hi @tomhughes! I think there's probably a version of a PR template that does address what @gravitystorm was talking about (most likely in the form of a checklist). This template does not try to do that. It's aim is to enforce a consistent PR description. If that doesn't make sense for this repo, I'm happy to close this PR. After all, this change is meant to make the lives of reviewers easier!

I can definitely remove the risk section. I've found that in other projects asking for a risk assessment can be a useful exercise for the contributor. It can also give the reviewer helpful context when testing. A worst case idea of "what could go wrong here" is what I mean by risk.

Thank you for your feedback.

[tordans]

I think this is a good template that will make thinks better for some PRs. I certainly does not harm the process, because one can always remove all this very easily when creating a PR that does not fit this schema.

I would also remove the risk section. And make the intro even more explicit on the PR section which is where all the "do squash, do rebase, no merge commits" part is written.

[tordans]

Suggested change

	<!--Please read the contributing guidelines before making a PR: https://github.com/openstreetmap/openstreetmap-website/blob/master/CONTRIBUTING.md-->
	<!--
	Please read the contributing guidelines before making a PR:
	https://github.com/openstreetmap/openstreetmap-website/blob/master/CONTRIBUTING.md
	Especially the section on how to present PRs:
	https://github.com/openstreetmap/openstreetmap-website/blob/master/CONTRIBUTING.md#pull-requests
	-->

[tordans]

Suggested change

	### Risks
	<!--Is this a low, medium, or high risk change? Explain why.-->

[rkoeze]

Thanks @tordans! I removed the risk section and added the link to the PR section of the contributing guidelines as you suggested.