Adjust columns on mobile view for step-list--detailed

[petesfrench]

Done

• Sets columns to 6 at a smaller breakpoint

Fixes #5002

QA

• Open demo
• Check that there is the content and title of the stepped list take the appropriate number of columns
• On merge remove this from ubuntu.com https://github.com/canonical/ubuntu.com/pull/13580/files#diff-f5a5b0429dba7d86dd96396c39539ab3a091d90536bccb9db008a3dbc487f83dR1506

Check if PR is ready for release

If this PR contains Vanilla SCSS code changes, it should contain the following changes to make sure it's ready for the release:

• PR should have one of the following labels to automatically categorise it in release notes:
  • Feature 🎁, Breaking Change 💣, Bug 🐛, Documentation 📝, Maintenance 🔨.
• Vanilla version in package.json should be updated relative to the most recent release, following semver convention:
  • if CSS class names are not changed it can be bugfix relesase (x.x.X)
  • if CSS class names are changed/added/removed it should be minor version (x.X.0)
  • see the wiki for more details
• Any changes to component class names (new patterns, variants, removed or added features) should be listed on the what's new page.

Screenshots

Mobile

Tablet

Desktop

[webteam-app]

Demo starting at https://vanilla-framework-5007.demos.haus

[bartaz]

@petesfrench There is some prettier formatting issue in one of the files.

Running dotrun test locally should catch it as well. Or if you have prettier VS Code plugin, it should highlight it as well.