Remove mandatory HRM requirement

[HRM Recommendations]
(Recommendations for HR Monitor)

I had a similar issue with Wahoo HRM failing. I have gone through 3 now. I picked up 2 Garmin Duals. Pretty happy so far. Cheaper than the Wahoo, no problems getting connected.

Personally, I think they should be required for the majority of races. And they are a valuable tool for training.