concurrency/generator: use inclusive range in iteration

Fixes #23

concurrency/generator.md

@@ -9,7 +9,7 @@ func Count(start int, end int) chan int {
     ch := make(chan int)
 
     go func(ch chan int) {
-        for i := start; i < end ; i++ {
+        for i := start; i <= end ; i++ {
             // Blocks on the operation
             ch <- i
         }