fix false example

Author: EvilKarter

README.md

@@ -75,11 +75,11 @@ Creates a new challenge for ALTCHA.
 
 ```php
 $options = new ChallengeOptions(
-    algorithm: ChallengeOptions::DEFAULT_ALGORITHM,
-    maxNumber: ChallengeOptions::DEFAULT_MAX_NUMBER,
+    algorithm: Algorithm::SHA256,
+    maxNumber: BaseChallengeOptions::DEFAULT_MAX_NUMBER,
     expires: (new \DateTimeImmutable())->add(new \DateInterval('PT10S')),
     params: ['query_param' => '123'],
-    saltLength: ChallengeOptions::DEFAULT_SALT_LENGTH
+    saltLength: 12
 );
 ```