CLI: update hub PR URL
# What does this PR do?

Keeps up with hub API changes, and updates the instruction to get the PR URL (which was returning an object)
_The documentation is not available anymore as the PR was closed or merged._<|||||>It is already recent enough: the change was added in `v0.10.0` (see `1.` in `v0.10.0` breaking changes), which is our current minimum version