Fix Broken Links

[brian-montgomery]

There are two broken links on the site:

• On the homepage, the "Help us launch loca11y.org" link no longer works, as we closed that fundraiser.
  • Instead, lets change the link to View the new ta11y.org, complete with Branding.
• On the volunteer page, the Content Team has a link to the learning page for the old ta11y.org. Let's update that to just the homepage (www.ta11y.org).