docs: add note about new APIs in v1.4 (#76)

Author: thymikee

docs/api.md

@@ -59,10 +59,14 @@ A method returning an array of `ReactTestInstance`s with matching props object.
 
 ### `getByType: (type: React.ComponentType<*>)`
 
+> Note: added in v1.4
+
 A method returning a `ReactTestInstance` with matching a React component type. Throws when no matches.
 
 ### `getAllByType: (type: React.ComponentType<*>)`
 
+> Note: added in v1.4
+
 A method returning an array of `ReactTestInstance`s with matching a React component type.
 
 ### `[DEPRECATED] getByName: (name: React.ComponentType<*>)`