Unify findings list with https://www.w3.org/2001/tag/findings

[jyasskin]

We have two lists of findings, at https://www.w3.org/2001/tag/findings and https://tag.w3.org/findings/. The tag.w3.org one has more recent findings, but is missing some old (probably discontinued) drafts. We should only have 1 list, and ideally it wouldn't be solely the responsibility of the Team Contact to keep it up to date.