Update config for Step decorators

Remove extra 'yml'
Add `steps:` to make the example more explicit.

Author: edno

docs/08-Customization.md

@@ -358,11 +358,11 @@ List of available step decorators:
 Step decorators can be added to suite config inside `steps` block:
 
 {% highlight yaml %}
-yml
-step_decorators:
-    - Codeception/Step/TryTo
-    - Codeception/Step/Retry
-    - Codeception/Step/ConditionalAssertion
+steps:
+    step_decorators:
+        - Codeception/Step/TryTo
+        - Codeception/Step/Retry
+        - Codeception/Step/ConditionalAssertion
 
 {% endhighlight %}
 
@@ -452,4 +452,4 @@ If you see you have a problem that can be solved using these extensions, then gi
 
 
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