Update whitespace chore docker image
The whitespace image is failing, so maybe we need to update the image: https://gitlab.com/gitlab-org/gitlab-docs/-/jobs/1041551309
Changed my mind, the MVC is to just use the lint-html
image, and install markdownlint at runtime: https://gitlab.com/gitlab-org/gitlab-docs/-/jobs/1045478848
Edited by Marcel Amirault