Allow manual preview deploys for PRs

[velavokr]

Hi Mintlify team,

can you please add a simple manual trigger to force preview deploy from a PR?

Any solution will do, be it a special comment (e.g. /mintlify preview), or a special label like mintlify:preview, or a button or workflow we can run manually. Whatever is easier to you.

Why we need this.

We're running into a recurring issue with preview deployment automation. When a PR is first opened, the bot sometimes decides to skip generating a preview. After that initial decision, there's no way to "change its mind": the PR stays skipped forever, even if documentation files are added or updated later.

This bites us in two common workflows:

1. Docs added after PR creation. We sometimes open a PR first (e.g., for automation or config changes) and only later add docs updates that affect the generated documentation. Because the preview was skipped at creation time, new docs commits never trigger a preview.

2. Release-branch flow. During releases we develop docs on a temporary release branch, then merge to the main documentation branch at rollout. While work is in progress, our PRs target the release branch, not the main documentation branch. So preview deploys never trigger. That means we can't share live previews during the most critical review window.

Why it's a pain for our documentation authors:

1. we lose a key feedback tool when we most need it,
2. and then we have to spend time recreating PRs in a hacky way just to trick a preview deploy into running.

As already said, any simple manual trigger for previews, no matter how rough, will improve our developer experience here. A special comment or label, or an ability to run the workflow manually will suffice.

Thank you!