docs: correct context tour line reference (#282)

Co-authored-by: nightcityblade <nightcityblade@gmail.com>

Author: nightcityblade

_content/tour/eng/context.article

@@ -339,7 +339,7 @@ until their Context is cancelled.
 
 On line 28, the main goroutine cancels its Context value and then waits on line 29
 for all ten of the goroutines to receive the signal before shutting down the program.
-Once the cancel function is called, all ten goroutines on line 41 will become
+Once the cancel function is called, all ten goroutines on line 14 will become
 unblocked and print that they have been cancelled. One call to cancel to cancel
 them all.