Update 030_ros_with_zeromq.md
Update 030_ros_with_zeromq.md

I think `without serialization` was a typo.
It seemed grammatically incorrect as well.
Please propose a different fix if my interpretation is wrong.
Po-Jen/design,ros2/design,gbiggs/design,cfpperche/design,gbiggs/design,Po-Jen/design,ros2/design,cfpperche/design,gbiggs/design,Po-Jen/design,cfpperche/design,gbiggs/design,ros2/design,gbiggs/design,Po-Jen/design,ros2/design,ros2/design,cfpperche/design,Po-Jen/design,cfpperche/design