Release feedback

[yuhongyi]

Address feedback from Release Notes
Addressed feedbacks are

• Handle the output dimension properly when n_envs ==0. Tested with all combinations of batch rasterizer/raytracer, n_envs=0/2, render_all_cams/camera.render. (I should write a unit test for this)
• Renamed scene.batch_render() to scene.render_all_cams()
• Updated Release Notes with the API change in set_pose