minor #10074 Remove typo in example constructor (vngrp)

This PR was submitted for the 4.1 branch but it was merged into the 4.0 branch instead (closes #10074).

Discussion
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Remove typo in example constructor

There was a small typo in the constructor usage in an example. It said '__constructor' instead of '__construct'. This commit simply changes that.

Commits
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81fac04 Remove typo in example constructor

Author: javiereguiluz

workflow/state-machines.rst

@@ -201,7 +201,7 @@ you can get this state machine by injecting the Workflow registry service::
     {
         private $workflows;
 
-        public function __constructor(Registry $workflows)
+        public function __construct(Registry $workflows)
         {
             $this->workflows = $workflows;
         }