Update Bob metapackage release instructions

Hi,

I'm trying to release a new version of Bob, but I'm having an issue with the release script.

What this suppose to mean? https://gitlab.idiap.ch/bob/bob.devtools/blob/51878163c8925664fb85ee945e5d663e44b6e828/bob/devtools/release.py#L571

Why ../../bob/README; I don't get it.

Can someone shine a light on me? ping @andre.anjos

thanks