Rover: add support scurve algorithm description

[xianglunkai]

https://ardupilot.org/dev/docs/rover-L1.html
The description of the current algorithm needs to be modified to maintain consistency with the current algorithm？

[rmackay9]

@xianglunkai,

Yes, indeed, I'll need to update the dev wiki navigation explanation. txs.

[Hwurzburg]

@rmackay9 still on your list?