Fix possible bugs in claim-from-faucet

The `claim-from-faucet` function seems to have two minor bugs in it:
* the `map-set` function should take three arguments, map-name, tuple_A, and tuple_B, but it seems like it was just taking two arguments
* the `err` function seems like it should take a `u1` and not a `1`

src/pages/smart-contracts/principals.md

@@ -106,9 +106,9 @@ faucet" could be implemented as so:
   (if (is-none (map-get? claimed-before (tuple (sender tx-sender))))
       (let ((requester tx-sender)) ;; set a local variable requester = tx-sender
         (begin
-            (map-set claimed-before { sender: requester, claimed: true })
+            (map-set claimed-before { sender: requester } { claimed: true })
             (as-contract (stx-transfer? u1 tx-sender requester))))
-      (err 1)))
+      (err u1)))
 ```
 
 In this example, the public function `claim-from-faucet`: