changelog.md in natural_number_string-0.2.0 vs changelog.md in natural_number_string-0.2.1

@@ -1,4 +1,15 @@
+<a name="0.2.1"></a>
+## [0.2.1](https://github.com/packsaddle/ruby-natural_number_string/compare/v0.2.0...v0.2.1) (2015-09-26)
+
+
+### Features
+
+* **positive:** add positive_integer_string? ([69ecf8a](https://github.com/packsaddle/ruby-natural_number_string/commit/69ecf8a))
+* **zero-or-positive:** add zero_or_positive_integer_string? ([6d3c46b](https://github.com/packsaddle/ruby-natural_number_string/commit/6d3c46b))
+
+
+
 <a name="0.2.0"></a>
 # [0.2.0](https://github.com/packsaddle/ruby-natural_number_string/compare/v0.1.0...v0.2.0) (2015-09-26)
 
 
 ### Features