clarify instructions suggesting existing delay

[ElliotMebane]

https://github.com/NeuroTechX/bci-workshop/blob/master/INSTRUCTIONS.md

instructions say:
...
Then, add the following to line 191 of bgapi.py and save:

time.sleep(.25)

Please clarify what the correct code snippet should be. I already have that sleep code on line 187 so I'm not sure if my code already had the fix applied. Also including it at 191 seems fine so I'll add it anyway.

[micuat]

I guess pygatt has been updated and the instruction is obsolete. I don't have a device to test but I will make a pull request anyways, so hopefully someone will pick this up and merge it @hubertjb @rcassani @jdpigeon