📝 Clarify guidance on using `async def` without `await` (#13642)

Co-authored-by: Sebastián Ramírez <[email protected]>

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 (somehow) doesn't have to communicate with anything else and wait for it to respond, use `async def`, even if you don't need to use `await` inside.
 
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