update quickstart md to suggest checking out 1.25 instead of 1.17

When you go through the quickstart documentation it asks you to go to checkout version 1.17.0. The thing is, since this guide is in the big bang repository the guide itself changes when you do this checkout and asks you to checkout version 1.15.0. This is confusing and will make the user unsure if any other steps they've done thusfar in the guide have been changed. Ideally we could have this file dynamically update to the most recent tag, but I wasn't sure how to do that with gitlab. Maybe the file can updated automatically on release?

EDIT: Using the version specified in gitrepository.yaml we are giving the user a command to automatically checkout the latest version. I also updated the helm list and expanded k to kubectl where applicable since it is not said in the doc to alias it.