add missinsg module

src/grung/examples.py

@@ -0,0 +1,11 @@
+from typing import List
+
+from grung.types import Field, Record
+
+
+class User(Record):
+    _fields = [Field("name"), Field("email", unique=True)]
+
+
+class Group(Record):
+    _fields = [Field("name", unique=True), Field("users", List[User])]