docs(errors/infdig): add a common example

Mention common cause of error is binding to a new array on every $digest loop.

Closes #6465

docs/content/error/$rootScope/infdig.ngdoc

@@ -14,4 +14,28 @@ $scope.$watch('foo', function() {
 });
 ```
 
+One common mistake is binding to a function which generates a new array every time it is called.  For example:
+
+```
+<div ng-repeat="user in getUsers()">{{ user.name }}</div>
+
+...
+
+$scope.getUsers = function() {
+  return [ { name: 'Hank' }, { name: 'Francisco' } ];
+};
+```
+
+Since `getUsers()` returns a new array, Angular determines that the model is different on each `$digest`
+cycle, resulting in the error.  The solution is to return the same array object if the elements have
+not changed:
+
+```
+var users = [ { name: 'Hank' }, { name: 'Francisco' } ];
+
+$scope.getUsers = function() {
+  return users;
+});
+```
+
 The maximum number of allowed iterations of the `$digest` cycle is controlled via TTL setting which can be configured via {@link ng.$rootScopeProvider $rootScopeProvider}.