Xamarin.Forms-Samples/HelloXamarinFormsXAML/HolaXamarinFormsXAML/packages/repositories.config

<?xml version="1.0" encoding="utf-8"?>
<repositories>
  <repository path="..\HolaXamarinFormsXAML\HolaXamarinFormsXAML.Android\packages.config" />
  <repository path="..\HolaXamarinFormsXAML\HolaXamarinFormsXAML.iOS\packages.config" />
  <repository path="..\HolaXamarinFormsXAML\HolaXamarinFormsXAML.WinPhone\packages.config" />
</repositories>