Create Markdownlint job

[nschonni]

Could take the basic format as currently done in dotnet/docs#31543 and replace the few repos that have copies of this similar files.

• Create reference job here. In what folder?
• Create problem match file here
• Replace downstream jobs and problem matcher files
  • https://github.com/dotnet/runtime/tree/main/.github/workflows
  • https://github.com/dotnet/docs/tree/main/.github/workflows

/cc @BillWagner I think this is the repo that I was thinking would be dotnet/workflows

[BillWagner]

Adding @IEvangelist @gewarren for their thoughts.

[IEvangelist]

Oh, yeah. I like that! I think it makes sense to take that approach, but I'm struggling to find the immediate benefit to doing this. This idea is to push us more towards using this repo as the source for custom GitHub Actions and compositions of composite GitHub Actions, right? What are the direct benefits to this — would the .markdownlint-cli2.jsonc config file be overridable in consuming repositories, or are you thinking it lives in this repository?

[nschonni]

I think the .markdownlint-cli2.jsonc would still live in the repos, so that it can be consumed by VSCode through the markdownlint plugin (it's bundled in the Docs Authoring Pack AFAIK).

The main benefit of the job being here is mostly in centralizing the problem matcher and keeping the actions/* dependencies up-to-date in one place. You could potentially control the version of the CLI as an optional config vs the current approach of installing the latest on each run.

An alternate config is having package.json and pinned versions in the repos, but common script packages like mdn/workflows#81. That probably doesn't make sense in this org, unless that's a path you want to take.