QA:Testcase CoreOS modifying kernel arguments

Description

Install Fedora CoreOS and modify kernel arguments as described in the documentation.

Setup

1. Download and verify the latest FCOS next image (pick the right image for your environment).

How to test

1. Create an Ignition file. When writing the configuration, add a kernel_arguments section following the example in the documentation. You don't necessarily have to use the same kernel arguments from the documentation, but you can.
2. Launch your Fedora CoreOS system using this Ignition file. See the Quickstart and the provisioning docs for a guide how to launch FCOS in most environments (bare metal, virtual, cloud, etc).

Expected Results

1. You can SSH successfully into your FCOS system.
2. The kernel arguments (as seen in the /proc/cmdline file) are as specified in the Ignition config.
3. The kernel arguments persist across reboots.
4. The kernel arguments can be removed/added/edited via rpm-ostree kargs as described in the documentation.
5. The linked documentation makes sense, nothing is obviously missing, and the instructions are clear.