Remove files for legacy docs

[heitortsergent]

What?

Remove the files for the legacy version of the k6 docs.

Checklist

• I have used a meaningful title for the PR.
• I have described the changes I've made in the "What?" section above.
• I have performed a self-review of my changes.
• I have run the npm start command locally and verified that the changes look good.

Related PR(s)/Issue(s)

Closes #1824.

[heitortsergent]

@jdbaldry would you mind taking a look at this? I just want to make sure I don't remove any files that we need for the repo to work correctly with the Grafana docs. 😅

Also, would it be hard to add a workflow to make sure the repo builds correctly?

[jdbaldry]

@jdbaldry would you mind taking a look at this? I just want to make sure I don't remove any files that we need for the repo to work correctly with the Grafana docs. 😅

Also, would it be hard to add a workflow to make sure the repo builds correctly?

There's a lot of deletions so it's a bit hard to know but I guess you're primarily interested in being able to run make docs and ensure the published docs aren't affected by the PR, right?

You can get a deploy preview if you make some trivial change to the docs/sources directory but we can also rely on the local test.

For CI, we check the docs build in the website before publishing: https://github.com/grafana/writers-toolkit/blob/main/publish-technical-documentation/action.yml#L22C1-L26C1. I can extract that step into a reusable workflow and add it to the CI for PRs in this repo if you'd like?

[heitortsergent]

I just realized it's 4000+ file deletions 😅😅. I think looking at the file structure in the local branch is easier to see what it's still there, but yeah, I think we just need to make sure make docs still works.

If we could add a workflow to check the docs build, and the deploy preview, that'd be awesome. 😄