Fix typo

Author: Wolwer1nE

src/about_pattern_matching.rb

@@ -169,7 +169,7 @@ def test_array_pattern
 
   # ------------------------------------------------------------------
 
-  # Hash patternis quite the same as Array pattern, but it expects #deconsturct_keys(keys) method
+  # Hash pattern is quite the same as Array pattern, but it expects #deconsturct_keys(keys) method
   # It works with symbol keys for now
 
   class LetterAccountant