Adjust main branch to use respectful language

[mazzystr]

/kind enhancement

What happened:
Current standard of this repos main branch name master is not respectful to some contributors and/or users of KubeVirt

What you expected to happen:
Please adjust the main branch name to main.

Anything else we need to know?:

• Repo admin privledges will be necessary. Please coordinate with @mazzystr

[cwilkers]

/close

[kubevirt-bot]

@cwilkers: Closing this issue.

In response to this:

/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.