RC Link Presets

[hyp0dermik-code]

Here or BF wiki?

[deadbytefpv]

Would be great to have under "Before First Flight" page. Either before the Blackbox section or after the Modes section.

Thanks!

[VitroidFPV]

It would be a good contribution to the BF wiki too though :)

[Nikhil Parikh]

done in #405 - although definitely should be followed up for betaflight