Add a skip link to the table of contents

[HaSistrunk]

Is your feature request related to a problem? Please describe.

Having a skip link for the table of contents improves UX for users who rely on the keyboard to navigate.

Describe the solution you'd like

Add a skip link to the table of contents as specified in the RAC Style Guide. This might be a little tricky because we'll need to have a consistent identifier to target where the link skips to, which is not #main in this case.

Additional context

The table of contents is unique on each page, and it is not a WCAG failure if we don't implement it, but would improve UX for long tables of contents.