update changelog

Changelog.md

@@ -1,5 +1,15 @@
 # Changelog
 
+##### v2.1
+* merge [pull reqeuest #45](https://github.com/jjgrainger/PostTypes/pull/45): add PHP 7.2 Compatibility
+* merge [pull reqeuest #46](https://github.com/jjgrainger/PostTypes/pull/46): Make sure the "orderby" query var is a string when sorting by columns.
+* merge [pull reqeuest #55](https://github.com/jjgrainger/PostTypes/pull/55): Fix column mismatch broken sort
+* merge [pull reqeuest #56](https://github.com/jjgrainger/PostTypes/pull/56): Grammar mistakes corrected
+* merge [pull reqeuest #61](https://github.com/jjgrainger/PostTypes/pull/61): Fix incorrect property types
+* merge [pull reqeuest #62](https://github.com/jjgrainger/PostTypes/pull/62): Allow for multiple taxonomies and post types to be added
+* merge [pull reqeuest #63](https://github.com/jjgrainger/PostTypes/pull/63): Update Taxonomy columns documentation
+* merge [pull reqeuest #64](https://github.com/jjgrainger/PostTypes/pull/64): Update minimum PHP version, phpunit and phpcs
+
 ##### v2.0.1
 * merge [pull reqeuest #19](https://github.com/jjgrainger/PostTypes/pull/19): Use wp_dropdown_categories function for post filtering selectbox
 * update minimum php version to 5.6