GitHub Action: Run markdownlint with reviewdog

Based on reviewdog/action-shellcheck

This action runs markdownlint with reviewdog on pull requests to improve code review experience.

Inputs

inputs:
  github_token:
    description: 'GITHUB_TOKEN.'
    default: '${{ github.token }}'
  ### Flags for reviewdog ###
  level:
    description: 'Report level for reviewdog [info,warning,error]'
    default: 'error'
  reporter:
    description: 'Reporter of reviewdog command [github-check,github-pr-review].'
    default: 'github-check'
  filter_mode:
    description: |
      Filtering mode for the reviewdog command [added,diff_context,file,nofilter].
      Default is added.
    default: 'added'
  fail_on_error:
    description: |
      Exit code for reviewdog when errors are found [true,false]
      Default is `false`.
    default: 'false'
  reviewdog_flags:
    description: 'Additional reviewdog flags'
    default: ''
  ### Flags for markdownlint-cli ###
  markdownlint_flags:
    description: "Options of markdownlint-cli command. Default: '.'"
    default: '.'

Example usage

.github/workflows/reviewdog.yml

name: reviewdog
on: [pull_request]
jobs:
  markdownlint:
    name: runner / markdownlint
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: markdownlint
        uses: reviewdog/action-markdownlint@v0
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          reporter: github-pr-review