Clarify usage of async def when no await is needed

docs/en/docs/async.md

@@ -40,7 +40,7 @@ def results():
 
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-If your application (somehow) doesn't have to communicate with anything else and wait for it to respond, use `async def`.
+If your application doesn't need to communicate with anything else or await a response, it's still safe to use `async def` -- even if there's nothing to `await`.
 
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