mention bool field in readme

Author: sloev

README.md

@@ -41,6 +41,7 @@ $ curl 'http://0.0.0.0:8080/me/123/birthdate?birthdate=2017-10-30'
 
 * **str** : `ex: ?message=hello world`
 * **int** : `ex: ?age=100`
+* **bool** : `ex: ?missing=false`
 * **datetime.datetime** : `ex: ?currentdate=2017-10-30T10:10:30 or 2017-10-30`
 * **datetime.date** : `ex: ?birthdate=2017-10-30`
 * **List[str]** : `ex: ?words=you,me,them,we`
@@ -55,4 +56,4 @@ You need to apply the `parse_query_args` decorator as the first one executed whi
 
 You should always have request as the first argument in your function in order to use `parse_query_args`.
 
-**Note** that `request` arg can be renamed and even type-annotated as long as it is the first arg.
+**Note** that `request` arg can be renamed and even type-annotated as long as it is the first arg.