Improvements based on use case partner feedback

[passalis]

This PR includes the following changes:

• Removed wrongly placed __init__.py.
• Included a python folder in projects where all python examples are placed to avoid mixing them with the C examples and ROS nodes.
• Improved structure of the documentation and toolkit to make it more user friendly.
• Improved projects documentation.
• A dedicated page that includes compatibility issues.
• Additional information on how to modify a docker image without rebuilding it.
• Information on how customizing ROS pipelines and running multiple tools
• Instructions on how to build custom docker images that do not include the whole toolkit
• Group ROS nodes based on the input they receive in order to make it easier for users to understand how to use them.

[stefaniapedrazzi]

Thank you for these improvements!

I think it would be also nice to add the two new pages "issues.md" and "customize.md" in docs/reference/index.md

[stefaniapedrazzi]

The index is fine.
Maybe I would just move the "Known issues" at the end, so that it is not one of the first page a user will read from the documentation.

[passalis]

I agree, I moved it to the bottom. I also added the labels for running the tests, just to be safe.

[passalis]

This is now ready for review again.

[stefaniapedrazzi]

Thank you!