Fix plane decomposition launch and run.sh

[Divelix]

I just started to explore this repo and found 2 typos I had to fix to be able to follow tutorial examples with turtlebot:

• build.sh creates image with name elevation_mapping_cupy:latest, while run.sh assumes this image named mktk1117/elevation_mapping_cupy:latest
• turtlesim_plane_decomposition_example.launch includes turtlesim_example.launch, when there is no such launch. I assumed that turtlesim_simple_example.launch should be included instead and then everything launched fine.

[mktk1117]

Thanks a lot for your PR!
For the first point, actually there should be a image called mktk1117/elevation_mapping_cupy:latest in the dockerhub.
Maybe it's better to have an option to choose which to use.

[Divelix]

Oh, ok, now it seems obvious. I will remove my change in image name and update README, it should be enough.