nvhw/sfu_tab: documentation fix
Special Function Unit to compute the, well, special functions:
- rcp (fp32): 1/x
- - rsqrt (fp32): 1/x**2
+ - rsqrt (fp32): 1/sqrt(x)
- sin and cos (fp32): sin(x) and cos(x), but computed in two stages:
- presin instruction reduces input modulo tau (aka 2pi), divides by
