PyAPI: add type of bpy.types.NodeSocket.links

Ref !128626

scripts/modules/bpy_types.py

@@ -1276,6 +1276,8 @@ class NodeSocket(_StructRNA, metaclass=_RNAMetaPropGroup):
         """
         List of node links from or to this socket.
 
+        :type: :class:`NodeLinks`
+
         .. note:: Takes ``O(len(nodetree.links))`` time."""
         links = (link for link in self.id_data.links
                  if self in (link.from_socket, link.to_socket))