Package is missing

[ashwinsivakumar-18]

package='mogi_trajectory_server',
need to clone https://github.com/MOGI-ROS/mogi_trajectory_server.git #mention it in the Read.me

[dudasdavid]

It's explained in the curriculum of week 3-4, I'll add some notes here later in case someone cannot find it.