minor #11400 [Workflow] Update usage.rst (noniagriconomie)

This PR was submitted for the master branch but it was merged into the 3.4 branch instead (closes #11400).

Discussion
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[Workflow] Update usage.rst

Hello,
Some minors improvements/fixes on the doc

I do not know if I should target another branch

Commits
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867ef6e Update usage.rst

Author: javiereguiluz

workflow/usage.rst

@@ -298,7 +298,7 @@ workflow leaves a place::
         public function onLeave(Event $event)
         {
             $this->logger->alert(sprintf(
-                'Blog post (id: "%s") performed transaction "%s" from "%s" to "%s"',
+                'Blog post (id: "%s") performed transition "%s" from "%s" to "%s"',
                 $event->getSubject()->getId(),
                 $event->getTransition()->getName(),
                 implode(', ', array_keys($event->getMarking()->getPlaces())),
@@ -322,7 +322,7 @@ Guard Events
 There are a special kind of events called "Guard events". Their event listeners
 are invoked every time a call to ``Workflow::can``, ``Workflow::apply`` or
 ``Workflow::getEnabledTransitions`` is executed. With the guard events you may
-add custom logic to decide what transitions that are valid or not. Here is a list
+add custom logic to decide what transitions are valid or not. Here is a list
 of the guard event names.
 
 * ``workflow.guard``
@@ -343,15 +343,16 @@ See example to make sure no blog post without title is moved to "review"::
             $title = $post->title;
 
             if (empty($title)) {
-                // Posts with no title should not be allowed
+                // Posts without title are not allowed
+                // to perform the transition "to_review"
                 $event->setBlocked(true);
             }
         }
 
         public static function getSubscribedEvents()
         {
             return [
-                'workflow.blogpost.guard.to_review' => ['guardReview'],
+                'workflow.blog_publishing.guard.to_review' => ['guardReview'],
             ];
         }
     }