next/policies: revert dropping the VPAT policy date

Reverts the change from commit 949b0c6
that removed the "Last Updated" date from the VPAT page.

As noted in issue #8478, the first thing someone looking at our VPAT
would want to know is when it was last changed. The date provides
important context for the accessibility information.

Fixes #8478

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: haraldschilly

src/packages/next/pages/policies/accessibility.tsx

@@ -30,6 +30,7 @@ export default function AccessibilityPage({ customize }) {
               <h1 style={{ fontSize: "28pt" }}>
                 CoCalc Voluntary Product Accessibility Template (VPAT)
               </h1>
+              <h2>Last Updated: July 3, 2019</h2>
             </div>
             <div style={{ fontSize: "12pt", overflowX: "auto" }}>
               <Accessibility />