Add accessibility linting

[joshuagraber]

• [x] Add eslint-plugin-vuejs-accessibility to the eslint config
• [x] Adjust the configuration settings
• [x] Fix any a11y issues raised by the plugin
• [x] Update documentation

This blog post is a good overview of how to implement.

[github-actions[bot]]

:tada: This issue has been resolved in version 3.0.0-beta.1 :tada:

The release is available on:

• npm package (@beta dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[github-actions[bot]]

:tada: This issue has been resolved in version 3.0.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: