Fix typo in documentation.

Author: ioquatix

context/best-practices.md

@@ -184,5 +184,3 @@ end
 ```
 
 It can be especially important to impose timeouts when processing user-provided data.
-
-## 

context/tasks.md

@@ -189,14 +189,19 @@ end
 barrier = Async::Barrier.new
 semaphore = Async::Semaphore.new(2, parent: barrier)
 
-jobs.each do |job|
-	semaphore.async(parent: barrier) do
-		# ... process job ...
+begin
+	jobs.each do |job|
+		semaphore.async do
+			# ... process job ...
+		end
 	end
-end
 
-# Wait until all jobs are done:
-barrier.wait
+	# Wait until all jobs are done:
+	barrier.wait
+ensure
+	# Stop any remaining jobs:
+	barrier.stop
+end
 ~~~
 
 ## Stopping a Task

guides/tasks/readme.md

@@ -189,14 +189,19 @@ end
 barrier = Async::Barrier.new
 semaphore = Async::Semaphore.new(2, parent: barrier)
 
-jobs.each do |job|
-	semaphore.async(parent: barrier) do
-		# ... process job ...
+begin
+	jobs.each do |job|
+		semaphore.async do
+			# ... process job ...
+		end
 	end
-end
 
-# Wait until all jobs are done:
-barrier.wait
+	# Wait until all jobs are done:
+	barrier.wait
+ensure
+	# Stop any remaining jobs:
+	barrier.stop
+end
 ~~~
 
 ## Stopping a Task

releases.md

@@ -1,5 +1,9 @@
 # Releases
 
+## Unreleased
+
+  - Fix typo in documentation.
+
 ## v2.32.0
 
   - Introduce `Queue#waiting_count` and `PriorityQueue#waiting_count`. Generally for statistics/testing purposes only.