Fix ignored_namespaces value: use regex pattern format

Author: OskarStark

.doctor-rst.yaml

@@ -26,7 +26,7 @@ rules:
             'src/': 'App\'
             'tests/': 'App\Tests\'
         ignored_namespaces:
-            - 'Acme\'
+            - '/^Acme\\\\/'
         ignored_paths:
             - '/^config\//'
             - '/^example\.com\//'