How to manually import the portable profile “portable-net45+win8”?

I am upgrading a .NET solution from .NET Core rc1 to rc2 following the instructions here: http://ef.readthedocs.io/en/latest/miscellaneous/rc1-rc2-upgrade.html

In the article it states 'The workaround is to manually import the portable profile “portable-net45+win8”.'

Can someone tell me how to manually import this profile please?

Actually next paragraph contains how to do this. Modify project.json file:

{
  "frameworks": {
    "netcoreapp1.0": {
      "imports": ["dnxcore50", "portable-net45+win8"]
    }
}