README.md in trackler-2.2.1.72

- old
+ new

@@ -56,18 +56,16 @@
 
 ## Step 3
 
 The weakest link in any cipher is the human being. Let's make your
 substitution cipher a little more fault tolerant by providing a source
-of randomness and ensuring that the key is not composed of numbers or
-capital letters.
+of randomness and ensuring that the key contains only lowercase letters.
 
 If someone doesn't submit a key at all, generate a truly random key of
-at least 100 characters in length, accessible via Cipher#key (the #
-syntax means instance variable)
+at least 100 characters in length.
 
-If the key submitted has capital letters or numbers, throw an
-ArgumentError with a message to that effect.
+If the key submitted is not composed only of lowercase letters, your
+solution should handle the error in a language-appropriate way.
 
 ## Extensions
 
 Shift ciphers work by making the text slightly odd, but are vulnerable
 to frequency analysis. Substitution ciphers help that, but are still