Add migration notes

Author: urfeex

doc/migration_notes.rst

@@ -0,0 +1,26 @@
+ur_client_library
+=================
+
+This document contains notes on the migration of the ur_client_library between major versions.
+
+It contains only breaking changes.
+
+Migrating from 1.x.x to 2.x.x
+-----------------------------
+
+- In the ``urcl::ExampleRobotWrapper`` class the ``ur_driver_``, ``dashboard_client`` and
+  ``primary_client`` members are now private. Use ``getUrDriver()``, ``getDashboardClient()`` and
+  ``getPrimaryClient()`` to access them.
+
+- In ``urcl::comm::ControlModeTypes`` two member functions have been renamed:
+
+  - ``is_control_mode_realtime`` -> ``isControlModeRealtime``
+  - ``is_control_mode_non_realtime`` -> ``isControlModeNonRealtime``
+
+- In ``urcl::RobotReceiveTimeout`` the ``timeout_`` member is now private. Use
+  ``getAsMilliseconds()`` to access it.
+
+- In ``urcl::UrDriverConfiguration`` two members have been renamed:
+
+  - ``rtde_initialization_attempts_`` -> ``rtde_initialization_attempts``
+  - ``rtde_initialization_timeout_`` -> ``rtde_initialization_timeout``