Show breaking change of API validation methods

Author: fulldecent

Documentation/Open Location Code API Specification.md

@@ -8,6 +8,7 @@ All substantial changes changes to this document are listed here.
   * Update to match nomenclature in [Plus Codes specification](./Plus%20Codes%20Specification.md)
   * Separate REQUIRED and OPTIONAL public methods
   * Specify the number of significant digits that a short code Plus Code may omit
+  * `isFull`, `isShort`, `isValid` methods must now validate whether the input actually is a valid Plus Code ignoring case (breaking change, previously `true` could be returned for some invalid inputs)
 
 - Version 1.0.0 / 2014-10-27 / [Doug Rinckes](https://github.com/drinckes), Google / Philipp Bunge, Google
   - Initial public release