github: Issue template is not working anymore

[tonistiigi]

https://github.com/moby/buildkit/blob/master/.github/issue_template.md?plain=1 is not showing up anymore when opening new issue in the repo. Looks like we need to move to some new format.

[polarathene]

If it helps, you just put together a .yml template in .github/ISSUE_TEMPLATE like this. Github has a documented example you can reference too.

---

You should only need to rename the file and add some frontmatter like this:

.github/ISSUE_TEMPLATE/issue.md:

---
name: Open an Issue
about: Feel free to report bugs, suggest features, or submit proposals here
---

<!---
Thank you for contributing to BuildKit through issue submission! If you're new to this repository, we encourage you to review our issue reporting guide https://github.com/moby/buildkit/blob/master/.github/issue_reporting_guide.md which outlines the key information you should provide for the process to go smoothly.

For general questions about using BuildKit, consider joining the #buildkit channel on the Docker Community Slack, where a broader community can provide support and insights.
--->

or migrate to the new yaml form schema .github/ISSUE_TEMPLATE/issue.yml:

name: Open an Issue
description: |
  Feel free to report bugs, suggest features, or submit proposals here
body:
  - type: markdown
    attributes:
      value: |
        Thank you for contributing to BuildKit through issue submission!
        - If you're new to this repository, we encourage you to review our [issue reporting guide](https://github.com/moby/buildkit/blob/master/.github/issue_reporting_guide.md) which outlines the key information you should provide for the process to go smoothly.
        - For general questions about using BuildKit, consider joining the `#buildkit` channel on the Docker Community Slack, where a broader community can provide support and insights.

  - type: textarea
    validations:
      required: true
    attributes:
      label: Description
      description: Share your bug report, feature request or proposal here
      placeholder: Type your description here...

name + description appear when selecting an issue template, so that you can have one for proposals, features, bug reports, etc that auto add some labels if you like.

The markdown one should provide the value below the frontmatter in a textarea field for the user to remove, whereas the YAML example should render markdown instead if you want that to remain visible. The 2nd type in the config is an actual input for the user, only the label attribute is mandatory.

[crazy-max]

Yes we aim to have something similar to buildx issue templates: https://github.com/docker/buildx/tree/master/.github/ISSUE_TEMPLATE