docs: fix missing underscore in field name idle_timeout (#16070)
docs: fix missing underscore in field name idle_timeout (#16070)

Signed-off-by: addozhang <c1c54c71dd97d814a7f582714fab613d1fbfcecd@gmail.com>
lyft/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,lyft/envoy