Update README.md broken link

[pascaloliv]

Description

Fix broken link to project structure documentation file.

[xem]

thanks, I approved it, however, the readme should probable be redirect to the github wiki, more up-to date. Do you agree? (if some info from the readme is missing in the wiki, we can add it there)

[pascaloliv]

Using the Github Wiki as main source of documentation is a good idea. Let's think about a little revamp of the README.md someday to fine-tune a little bit more the first contact with the codebase.