[Feature] Add border tokens to Storybook documentation

[jessicawoodin]

Description of Change

• Updated tokens version number in package.json
• Added border-strong and border-subtle to Storybook documentation

PR Checklist

Code reviewer validation:

• General
  • PR is linked to ticket(s)
  • PR has changelog label applied if it's to be included in the changelog
  • Acceptance criteria:
    • All satisfied or
    • Documented reason for not being performed or
    • Split to separate ticket and ticket is linked by relevant AC(s)
  • Above PR sections adequately filled out
  • If any breaking changes, in accordance with the pre-1.0.0 versioning guidelines: a CU ticket has been created for the VA Mobile App detailing necessary adjustments with the package version that will be published by this ticket
• Code
  • Tests are included if appropriate (or split to separate ticket)
  • New functions have proper TSDoc annotations

Publish

Changes do not warrant a new version per the versioning guidelines.

[narin]

Looks good! For future PRs, please include a screenshot of the changes in the PR description if applicable.