Update feed about and link to point at the production URI

• Update feed about and link to point at the production URI

To make routing easier and reduce overall complexity, we will instead point the alternate form of the known vul'n page to this RSS feed rather than doing backend proxy passing to show this content within the Eclipse.org site.

requested review from @cguindon, @malowe, and @zacharysabourin

approved this merge request

mentioned in commit 62ccf9af

merged