Clarify image paths for track documentation

[kytrinyx]

We need the path to start with a slash, and be the full path from the root of the repository.

This is an absolute path, if you consider the repository root.

I'm still not sure I am explaining this clearly.

Thanks @joelwallis for catching this. :sparkles:

[verdammelt]

👍 as long as I understand what you are trying to say :) (and I think I do...)

[joeljuca]

👍