feat: link PDS in first onboarding step to official docs

static/onboarding.js

···
     {
         target: '.identity',
         title: 'this is you',
-        description: 'your global identity and handle. your data is hosted at your Personal Data Server (PDS).',
+        description: 'your global identity and handle. your data is hosted at your <a href="https://atproto.com/guides/overview" target="_blank" rel="noopener noreferrer" style="color: inherit; text-decoration: underline;">Personal Data Server (PDS)</a>.',
         position: 'bottom'
     },
     {