Update message-passing.mdx

Author: jsundai

docs/develop/php/message-passing.mdx

@@ -904,8 +904,8 @@ Use [`Workflow::registerDynamicUpdate()`](https://php.temporal.io/classes/Tempor
 
 The method accepts two arguments:
 
-- Update Handler.
-- Update Validator (optional) that should throw an exception if the validation fails.
+- Update Handler
+- Update Validator (optional) that should throw an exception if the validation fails
 
 Both, the Handler and the Validator must accept a `string` name and [`ValuesInterface`](https://php.temporal.io/classes/Temporal-DataConverter-ValuesInterface.html) for the arguments.