better don‘t expect such resources to be useful - darktable isn’t focused on editing by numbers. So if you want to learn about RGb Parade or histogram each tool sepecific and tool agnostic documentation won’t give less information regarding darktable …
If you’re thinking about their darktable 4 book, the benefit over the official darktable documentary is a proper german and illustrated description of the modules and a workflow centric structure.
But also not about editing by numbers 
If you want to get a technical understanding then read whatever description or watch explanation videos you can find in the internet provided by the authors of modules. you might have a look here: Understanding of filmic rgb - #4 by MStraeten