Add "check-github-issue-config" pre-commit hook

[vivodi]

GitHub Issue Config are very commonly used—almost every repository uses them. It would be great if there were a ready-made hook for them.

Moreover, a custom hook created with “check-jsonschema” cannot run on pre-commit.ci because pre-commit.ci only provides network access at installation time, not at runtime. This means that a custom hook created with “check-jsonschema” is effectively unusable in CI. As a repository maintainer, you cannot know whether a PR has truly passed the pre-commit hooks checks. Therefore, it is strongly recommended to integrate it into the repository as a hook named "check-github-issue-config".

My custom hook works in all scenarios:

- id: check-jsonschema
  name: Check GitHub Issue Config
  files: ^\.github/ISSUE_TEMPLATE/config\.yml$
  args:
    [--schemafile, https://www.schemastore.org/github-issue-config.json]