docs: Update macOS plugin docs again

docs: Update macOS plugin docs again

Contains the following updates:

* New properties on avfvideosrc: screen-crop-*
* H265 and H265 Alpha support in vtdec and vtenc (VideoToolbox)
* ProRes support in vtenc
* New properties on vtenc elements: rate-control, data-rate-limits,
  max-frame-delay
* New plugin atenc (AudioToolbox) with support for encoding AAC
* Plugin move: atdec moved from -bad to -good
* New property on osxaudio elements: unique-id
* OS X -> macOS

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8120>