Update exercises/intergalactic-transmission/instructions.md

Author: ryanplusplus

exercises/intergalactic-transmission/instructions.md

@@ -7,7 +7,7 @@ Your job is to help implement
 
 A parity bit is simple way of detecting transmission errors.
 The transmitters and receivers can only transmit and receive _exactly_ eight bits at a time (including the parity bit).
-The parity bit is set so that there is an _even_ number of 1s in each transmission, and the parity bit is always the first bit from the right.
+The parity bit is set so that there is an _even_ number of 1 bits in each transmission, and the parity bit is always the first bit from the right.
 So if the receiver receives `11000001`, `01110101` or `01000000` (i.e. a transmission with an odd number of 1 bits), it knows there is an error.
 
 However, messages are rarely this short, and need to be transmitted in a sequence when they are longer.