Add an option to mark created PRs as draft

[another-novelty]

Tell us more.

Sometimes a manual action has to be done before a version can be upgraded, like extracting a SHA-sum of a binary and inserting it in the build-script.

To prevent anyone from mindlessly merging the created PR, we like to mark it as a draft. Right now, this is perfectly doable by prefixing the commit message with "DRAFT: ". The generated PR-title will also have the prefix, and gitlab (I don't know how github handles this) will not allow merging.

However, we think it would be nicer still to have a simple boolean which would prepend the prefix to the auto-generated message. This way, any changes to the default template would not have to be carried downstream.

[another-novelty]

I found this documentation. It should probably be linked in the template config documentation

[another-novelty]

Correct, I just would want a mention of that option in the documentation for the templating so that others would not have to go through this rabbit hole.

[rarkins]

So an added note in the draftPr docs which says "For unsupported platforms or custom draft conventions, refer to [...] for instructions on changing built-in templates?

[another-novelty]

No the other way round.

[rarkins]

Sorry, but I don't agree on this one, for these reasons:

1. We shouldn't link from the templates page to every possible reason why you might template, as it will balloon the page out, and suddenly have people raising 50 discussions like this saying that something is "missing"
2. If someone's job to be done is draft PRs, at least 90% of the time they should have searched for draft PRs and found the feature which is literally called draftPr.

[another-novelty]

Alright then