update gcloud command for Cloud Tasks [(#1566)](GoogleCloudPlatform/python-docs-samples#1566)

* update gcloud command

* update pull queue command

* update pull queue command

Author: averikitsch

samples/snippets/README.md

@@ -28,25 +28,23 @@ To set up authentication, please refer to our
 
 To create a queue using the Cloud SDK, use the following gcloud command:
 
-    gcloud alpha tasks queues create pull my-pull-queue
+    gcloud beta tasks queues create-pull-queue my-pull-queue
 
 ## Running the Samples
 
 Set the environment variables:
 
-Set environment variables:
-
 First, your project ID:
 
     export PROJECT_ID=my-project-id
 
 Then the queue ID, as specified at queue creation time. Queue IDs already
-created can be listed with `gcloud alpha tasks queues list`.
+created can be listed with `gcloud beta tasks queues list`.
 
     export QUEUE_ID=my-pull-queue
 
 And finally the location ID, which can be discovered with
-`gcloud alpha tasks queues describe $QUEUE_ID`, with the location embedded in
+`gcloud beta tasks queues describe $QUEUE_ID`, with the location embedded in
 the "name" value (for instance, if the name is
 "projects/my-project/locations/us-central1/queues/my-pull-queue", then the
 location is "us-central1").