minor #5594 Missing --no-interaction flag? (alexwybraniec)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #5594).

Discussion
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Missing --no-interaction flag?

Running
php app/console doctrine:generate:entity --entity="AppBundle:Category" --fields="name:string(255)"
does not automatically generate the entity.

Needs the --no-interaction flag set or it enters the interactive generator.

Commits
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478023c Missing --no-interaction flag?

Author: wouterj

book/doctrine.rst

@@ -904,7 +904,7 @@ you can let Doctrine create the class for you.
 
 .. code-block:: bash
 
-    $ php app/console doctrine:generate:entity \
+    $ php app/console doctrine:generate:entity --no-interaction \
         --entity="AppBundle:Category" \
         --fields="name:string(255)"