Fix a variable spelling mistake. (#563)

eBook/14.2.md

@@ -551,7 +551,7 @@ func sink(ch <-chan int) {
 
 ```go
 sendChan := make(chan int)
-reciveChan := make(chan string)
+receiveChan := make(chan string)
 go processChannel(sendChan, receiveChan)
 
 func processChannel(in <-chan int, out chan<- string) {