Fix units in Rhs2116DataFrame xml comment

[cjsha]

I'm guessing the mv needs to be µV.

The offending lines:

bonsai-onix1/OpenEphys.Onix1/Rhs2116DataFrame.cs

Line 48 in 634a54c

/// V_electrode (mV) = -19.23 mV × (ADC result – 512)

bonsai-onix1/OpenEphys.Onix1/Rhs2116DataFrame.cs

Line 34 in 634a54c

/// V_electrode (uV) = 0.195 µV × (ADC result – 32768)

I linked the second line as well because we use "uV" in the first instance and "µV" in the second instance.

This screenshot shows what I'm referring to. Look at the (micro-/milli-)Volt units.

[jonnew]

The only change that seems to be required is that in the DCData description, last sentence should be "To convert to millivolts"

Also, while we are at it, remove dashes between micro-volts and milli-volts.