minor #9852 add missing option in yaml configuration (shinmen)

This PR was merged into the 4.0 branch.

Discussion
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add missing option in yaml configuration

Add enabled: true in framework.profiler configuration in yaml example.
xml and php examples are ok.

Commits
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5a73a17 add missing option in yaml configuration

Author: javiereguiluz

testing/profiling.rst

@@ -25,7 +25,7 @@ tests significantly. That's why Symfony disables it by default:
 
         # ...
         framework:
-            profiler: { collect: false }
+            profiler: { enabled: true, collect: false }
 
     .. code-block:: xml