doc: fix "sign.verify" typo in crypto doc.

Fix typo in example

PR-URL: #7411
Reviewed-By: Brian White <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>
Reviewed-By: James M Snell <[email protected]>

doc/api/crypto.md

@@ -794,7 +794,7 @@ verify.end();
 
 const public_key = getPublicKeySomehow();
 const signature = getSignatureToVerify();
-console.log(sign.verify(public_key, signature));
+console.log(verify.verify(public_key, signature));
   // Prints true or false
 ```