Fix Prettier formatting in spacing docs shortcodes

[mdo]

Description

Reformats the SpacingNotation.astro and SpacingResponsive.astro docs shortcodes to satisfy docs-prettier-check.

Motivation & Context

The Lint CI job on v6-dev was failing because docs-lint → docs-prettier-check flagged unformatted code in these two shortcodes (introduced in #42454). The changes are purely stylistic line-reflow and explicit whitespace markers, so rendered output is unchanged. Verified with npm run docs-prettier-check.

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

• https://deploy-preview-{your_pr_number}--twbs-bootstrap.netlify.app/

Related issues

🤖 Generated with Claude Code