Add state shape documentation

src/state/ducks/auth/reducer.js

@@ -2,6 +2,13 @@ import { handleActions } from 'redux-actions';
 
 import * as types from './types';
 
+/* auth reducer state shape:
+{
+  // true iff the user is authenticated
+  authenticated: boolean,
+}
+*/
+
 const defaultState = {
   authenticated: false,
 };

src/state/ducks/navigation/reducer.js

@@ -5,6 +5,8 @@ import { RawNavigator } from '../../../navigation/AppNavigator';
 const initialAction = RawNavigator.router.getActionForPathAndParams('Login');
 const initialState = RawNavigator.router.getStateForAction(initialAction);
 
+// state shape is defined by react-navigation
+
 export default function reducer(state = initialState, action) {
   const nextState = RawNavigator.router.getStateForAction(action, state);
   return nextState || state;

src/state/ducks/patreon/reducer.js

@@ -8,6 +8,19 @@ import {
   PATREON_ERROR,
 } from './types';
 
+/* patreon reducer state shape:
+{
+  // true iff the user has connected Patreon
+  enabled: boolean,
+
+  // true iff we are waiting for a response from the Patreon API
+  loading: boolean,
+
+  // if not null, the error from the last Patreon API call
+  error: ?Error,
+}
+*/
+
 const defaultState = {
   enabled: false,
   loading: false,