Added robotpkg in the installation explanations
As suggested here (https://gepgitlab.laas.fr/gepetto/example-robot-data/issues/4#note_3439), I added both robotpkg sources in the installation instructions (REAME file).
Edited by Carlos Mastalli
As suggested here (https://gepgitlab.laas.fr/gepetto/example-robot-data/issues/4#note_3439), I added both robotpkg sources in the installation instructions (REAME file).