Create README.md in Each Top-Level Folder Under src

Expected behavior

Each top-level folder under Autoware.Auto/src should contain modules specific to a domain, with the exception of common. To facilitate this, it would be useful to have a README.md file in each folder describing what should be contained within that folder.

Definition of Done

• Create a README.md file in each root folder under src to describe the domain and examples of what should and should not be included in the folder.
• Consider using the README.md files as the indices for doc auto-generation.