Practice 4 - pure_pursuit_follower - code comments

[geopimik]

Please fix following:

1. Move this group below Parameters and you can name them as global variables https://github.com/jaak-peterson/autoware_mini_practice/blob/7df7b776cd80ca3a60784d6644eb98fbcd7ac4b5/practice_4/nodes/control/pure_pursuit_follower.py#L15-L16

2. Change queue_size to 1. Here the old commands are not relevant we have new commands coming up with 50hz and if they are put in the queue then it is processed using First in First out (FIFO) principle. If there would be some lags and our node would not manage to process them all the newer commands would be skipped and we would be using older commands from the queue. By using 1 here we guarantee always to have the latest command available. https://github.com/jaak-peterson/autoware_mini_practice/blob/7df7b776cd80ca3a60784d6644eb98fbcd7ac4b5/practice_4/nodes/control/pure_pursuit_follower.py#L23

3. Some comments you need to fix in follower are still open from the last practice: #2

[geopimik]

1. OK
2. OK
3. TODO

[geopimik]

OK