Safety instructions (SAFETY.md)

[alphaville]

Main Changes

SAFETY.md is introduced: a document that attempts to identify the key hazards in the lab (e.g., soldering, handling LiPo batteries, and working with quadcopter motors) and propose a number of safety measures.

[alphaville]

@jamie-54 @gunturiCM: reminder

[jamie-54]

I'm happy with it

[patchedByBatman]

Please look into these.

1. In section 5.1, Voltage deviation, typo in 5mV ~ 10Mv, which should be 5mV ~ 10mV.
2. In section 6.2, point 4, typo: "pinning propellers".
3. What does esp mean in section 9, point 2, sub-point 1? Is that a typo?

[alphaville]

2. pinning

Thanks, @gunturiCM

1. Fixed
2. [s]pinning - fixed
3. "esp." stands for especially