Update CHANGELOG.md

Added link to docs in CHANGELOG.md

Author: Calvin Alkan

CHANGELOG.md

@@ -11,7 +11,7 @@
 
 ### Added
 
-- Smart default values - You can now typehint the return value on your event's `default()` method. If the typehint does not match with the filtered value the default() method will get called with the original and filtered value. ([Commit](https://github.com/calvinalkan/better-wordpress-hooks/commit/8d564babae2f448f607ceb1aea73edae487d2bfc#diff-6f76b222b1d42b154e0ca5f9cca9c766227cb56a75f7bff262e412a5f85a9378R182))
+- Smart default values - You can now typehint the return value on your event's `default()` method. If the typehint does not match with the filtered value the default() method will get called with the original and filtered value. ([Usage](https://github.com/calvinalkan/better-wordpress-hooks/tree/0.1.5#return-values-for-invalid-callback))([Commit](https://github.com/calvinalkan/better-wordpress-hooks/commit/8d564babae2f448f607ceb1aea73edae487d2bfc#diff-6f76b222b1d42b154e0ca5f9cca9c766227cb56a75f7bff262e412a5f85a9378R182))
 - It's now possible to resolve mapped events from the service container ([Commit](https://github.com/calvinalkan/better-wordpress-hooks/commit/3b48f0b7951c28e1f1c8ff7ce94ce7e842e89ef6)). See example under [Bootstrapping](https://github.com/calvinalkan/better-wordpress-hooks/blob/master/README.md#bootstrapping).
 
 ### Changed