coroutine: fix a typo in comment
coroutine: fix a typo in comment

Signed-off-by: Kefu Chai <cdc92d111bae0ed1ee3b3c8a1f849fcffc6b44f7@gmail.com>
Message-Id: <20220524095718.3264616-1-cdc92d111bae0ed1ee3b3c8a1f849fcffc6b44f7@gmail.com>

scylladb/seastar,syuu1228/seastar,scylladb/seastar,avikivity/seastar,syuu1228/seastar,scylladb/seastar,avikivity/seastar,avikivity/seastar,syuu1228/seastar