Update _vercel.alexander.json

This PR corrects the TXT record for the _vercel.alexander.is-a.dev configuration.
The previous record included an extra prefix (vercel-site-verification=) which prevented Vercel from validating the domain.

Updated TXT value:
vc-domain-verify=alexander.is-a.dev,d49036035013a0d0d8b6

This change ensures successful verification of the domain with Vercel.

domains/_vercel.alexander.json

@@ -4,6 +4,6 @@
     "email": "aalexlpez@gmail.com"
   },
   "records": {
-    "TXT": "vercel-site-verification=vc-domain-verify=alexander.is-a.dev,d49036035013a0d0d8b6"
+    "TXT": "vc-domain-verify=alexander.is-a.dev,d49036035013a0d0d8b6"
   }
 }