Update documentation to match renamed primary branch

[sftim]

This is a Bug Report

Problem:
This k/website repo is renaming its primary branch to main. However, existing documentation refers to the old name: master.

Proposed Solution:
Update the affected pages.

Page to Update:
https://kubernetes.io/

Additional Information:
This is a tracking issue.
/language en

[k8s-ci-robot]

@sftim: This issue is currently awaiting triage.

SIG Docs takes a lead on issue triage for this website, but any Kubernetes member can accept issues by applying the triage/accepted label.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[sftim]

@jimangel FYI

[jimangel]

Looks like everything is merged and completed. Thanks again for your help!
/close

[k8s-ci-robot]

@jimangel: Closing this issue.

In response to this:

Looks like everything is merged and completed. Thanks again for your help!
/close

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.