Document Group's move in the public API

Author: jakirkham

docs/api/hierarchy.rst

@@ -36,3 +36,4 @@ Groups (``zarr.hierarchy``)
     .. automethod:: zeros_like
     .. automethod:: ones_like
     .. automethod:: full_like
+    .. automethod:: move

zarr/tests/test_hierarchy.py

@@ -688,6 +688,9 @@ def test_delitem(self):
     def test_move(self):
         g = self.create_group()
 
+        data = np.arange(100)
+        g['boo'] = data
+
         data = np.arange(100)
         g['foo'] = data
 
@@ -719,6 +722,12 @@ def test_move(self):
             assert 'bar' in g
             assert isinstance(g['foo2'], Group)
             assert_array_equal(data, g['bar'])
+
+            with assert_raises(ValueError):
+                g2.move('bar', 'bar2')
+
+            with assert_raises(ValueError):
+                g.move('bar', 'boo')
         except NotImplementedError:
             pass