aria-labelledby example with id and components

[andrewharvey]

The documentation at https://v3.vuejs.org/guide/a11y-semantics.html#labels shows using aria-labelledby however with Vue Components that breaks down as id is global within the page rather than local in scope to your component. I feel the documentation could do this a more vue way allowing components to be re-used multiple times within the page while still doing aria-labelledby.

For example something like https://github.com/vuejs/vue/issues/5886#issuecomment-308607131 works well.