Update conditions.rst

Undocumented functionality -> injecting container parameters into Route condition

Author: kockodev

routing/conditions.rst

@@ -87,3 +87,7 @@ variables that are passed into the expression:
 
     Because of this, using the ``condition`` key causes no extra overhead
     beyond the time it takes for the underlying PHP to execute.
+
+.. parameters-block:: Injecting parameters
+
+    You can inject container parameters (e.g. `%kernel.environment%`) into condition, such as `@Route(condition="'%kernel.environment' in ['dev']")` or any other you want.