Add values to tempoary ignore list in link linter

Why is this change being made?

Small change in preparation for the migration of the company values page. I have added '/handbook/values' to the temporary ignore list as we'll be setting up a redirect to from the about site to the handbook site which means the relative links in the handbook won't break. This will greatly reduce the number of links we need to rewrite in the handbook as a result of the migration. It also means that when we migrate subsequent content we won't need to rewrite those links.

Resolves gitlab-com/content-sites/handbook#75 (closed)

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