docs/api_reference: order the types in a logical order

Author: bluetech

docs/api_reference.rst

@@ -14,10 +14,15 @@ API Reference
 
 .. autodecorator:: pluggy.HookimplMarker
 
-.. autoclass:: pluggy.Result()
-    :show-inheritance:
+.. autoclass:: pluggy.HookRelay()
     :members:
 
+    .. data:: <hook name>
+
+        :type: HookCaller
+
+        The caller for the hook with the given name.
+
 .. autoclass:: pluggy.HookCaller()
     :members:
     :special-members: __call__
@@ -26,11 +31,6 @@ API Reference
     :show-inheritance:
     :members:
 
-.. autoclass:: pluggy.HookRelay()
+.. autoclass:: pluggy.Result()
+    :show-inheritance:
     :members:
-
-    .. data:: <hook name>
-
-        :type: HookCaller
-
-        The caller for the hook with the given name.