Update DNS records in keir.json

Added MX and TXT records for email forwarding.

domains/keir.json

@@ -4,6 +4,14 @@
     "email": "keirsalterego@gmail.com"
   },
   "records": {
-    "CNAME": "keir.vercel.app"
+    "CNAME": "keir.vercel.app",
+    "MX": [
+      "mx1.forwardemail.net",
+      "mx2.forwardemail.net"
+    ],
+    "TXT": [
+      "v=spf1 a mx include:spf.forwardemail.net ~all",
+      "forward-email=manish:keirsalterego@gmail.com"
+    ]
   }
 }