Previous, SW1 was too close to RST, making it difficult to press one
without pressing another. After changing its position, it was more
convenient to route SW1 to pin 10 on U1 - That's P0.30/AIN6 both on
nRF52840 (C) and nRF52833 (E) modules.
I previously used a basic 2N3906 and then changed its footprint to
SOT-23. This led to the wrong pin assignment.
This commit fixes it by using the correct symbol and footprint for it.
Note that the PCB layout still needs fixing.
- Simplified the fast discharge circuit to use a single PNP BJT instead
of two NPN BJTs
- Swapped nRF52 module's footprint for one with larger pads
- Added a user button tied to P0.12 (same as Button 2 from [nrf52840_dk](https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf52840_dk%2FUG%2Fdk%2Fhw_buttons_leds.html))
- Added a reset switch
These are only schematic changes - PCB layout is stale and needs to be
recreated.
