Updating Changelog to reflect error handling changes

Author: leofischer

CHANGELOG.md

@@ -3,6 +3,7 @@
 - Standardizes `PaymentMethod` as a child of `ChargeParams` to avoid nomenclature inconsistencies in the rest of the project
 - Corrects Broken MSI specs
 - Adds Subscription/Plan Support
+- 402 ProcessingError now returns the modified object rather than throw an error, as a user you need to check the return status to determine whether or not it was successful
 
 ## [1.0.0](https://github.com/conekta/conekta-php/releases/tag/v1.0.0) - 2020-01-20
 ### Feature