[Intel-gfx] [PATCH i-g-t 1/3] intel_gpu_top: Update manual page for recent additions

[Chris Wilson]

Quoting Tvrtko Ursulin (2021-02-01 10:45:22)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Document numeric busyness overlay and sort selection.

I looked for a 'h' or '?' screen.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris