chore: update linting tools and configuration

Description

Add markdownlint-cli2 as asdf dependency, so both linters are available to asdf users.

Also, now that we have a Docker image (https://gitlab.com/gitlab-org/gitlab-docs/-/jobs/7981643564) with the latest markdownlint-cli2 in it (https://github.com/DavidAnson/markdownlint-cli2/compare/v0.13.0...v0.14.0), let's use it!

Let's also update our linter configuration from gitlab project.

Job that uses new Docker image: https://gitlab.com/gitlab-org/gitlab-vscode-extension/-/jobs/7991801194.

What CHANGELOG entry will this MR create?

• fix: Bug fix fixes - a user-facing issue in production - included in changelog
• feature: New feature - a user-facing change which adds functionality - included in changelog
• BREAKING CHANGE: (fix or feature that would cause existing functionality to change) - should bump major version, mentioned in the changelog
• None - other non-user-facing changes