Fix articles/ros2_threat_mode.md style issues (#238)
Fix articles/ros2_threat_mode.md style issues (#238)

- Fix most of the issues reported by mdl
- Each sentence starts on a new line

Fix #237

Signed-off-by: Thomas Moulard <c497402a3dadb29b8ae64e0cc05b0fff58b28660@amazon.com>
ros2/design,gbiggs/design,ros2/design,ros2/design,gbiggs/design,gbiggs/design,gbiggs/design,ros2/design,gbiggs/design,ros2/design