Update instrumentation/opentelemetry-instrumentation-asyncio/README.rst

Co-authored-by: Aaron Abbott <[email protected]>

Author: bourbonkk

instrumentation/opentelemetry-instrumentation-asyncio/README.rst

@@ -25,7 +25,7 @@ If you want to trace specific blocking functions executed with the ``to_thread``
 
     export OTEL_PYTHON_ASYNCIO_TO_THREAD_FUNCTION_NAMES_TO_TRACE=func_name,func_name2,func_name3
 
-For future, set it up like this
+You can enable tracing futures with ``OTEL_PYTHON_ASYNCIO_FUTURE_TRACE_ENABLED``
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 .. code:: bash