Add a task page for setting up kuberc

**This is an umbrella issue**

**What would you like to be added**
Add a new task page that explains how to write a kuberc file, which allows customizing kubectl behavior.

**Why is this needed**
With the work around [kuberc](https://github.com/kubernetes/enhancements/issues/3104) we need to ensure there's a proper documentation in place, so users can understand how to correctly leverage the file and make kubectl easier to use for them,.

**Comments**
Partially addressed by https://github.com/kubernetes/website/pull/50913 and https://github.com/kubernetes/website/pull/50961.

Start by reviewing pull requests 50913 and 50961 and the linked kuberc enhancement issue, since this umbrella issue is already partially addressed. Done means the Kubernetes website has a task page explaining how to write a kuberc file and use it to customize kubectl behavior.

Written by the indexing model from the issue text.