minor #15894 correction on a command to work (Cellophile)

This PR was submitted for the 5.3 branch but it was merged into the 4.4 branch instead.

Discussion
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correction on a command to work

After many tests, I've understood that the command was wrong : with two \\, it can't works, but with one, it's ok.
I think the documentation will be more efficient with the right command ! :)

Commits
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6a0f45c correction on a command to work

Author: javiereguiluz

doctrine/reverse_engineering.rst

@@ -103,7 +103,7 @@ run:
     $ php bin/console make:entity --regenerate App
 
     // generates getter/setter methods for one specific Entity
-    $ php bin/console make:entity --regenerate App\\Entity\\Country
+    $ php bin/console make:entity --regenerate App\Entity\Country
 
 .. note::