incorrect references about lookahead not supported at 4k

[shaunclimbon]

2.0 release added support for lookahead at 4k but multiple conflicting references still exist in the documentation:

• https://xilinx.github.io/video-sdk/v2.0/examples/ffmpeg/tutorials.html?highlight=lookahead#encoding-streams-to-4k
  • "The lookahead feature is not supported for 4k. FFmpeg will give an error if -lookahead_depth is enabled when encoding to 4k."
• https://xilinx.github.io/video-sdk/v2.0/specs_and_features.html#video-codec-unit
  • "Look-ahead driven video quality improvements through temporal adaptive and spatial adaptive quantization for resolutions up to 1080p"

[NastoohX]

Hi, Thank you for bringing this to our attention. Appropriate corrections will be made ASAP. Cheers,

[ThomasXilinx]

The documentation has now been updated accordingly.