fixup! refactor: extract definer

Author: fahchen

lib/typed_structor.ex

@@ -31,6 +31,20 @@ defmodule TypedStructor do
 
     * `:define_struct` - if `false`, the type will be defined, but the struct will not be defined. Defaults to `true`.
 
+  ### custom definer
+
+      defmodule MyStruct do
+        # you must require the definer module to use its define/1 macro
+        require MyDefiner
+
+        use TypedStructor
+
+        typed_structor definer: &MyDefiner.define/1 do
+          field :name, String.t()
+          field :age, integer()
+        end
+      end
+
   ## Examples
 
       defmodule MyStruct do