Replace vmware with goharbor in README

[bupd]

Thank you for contributing to Harbor!

Comprehensive Summary of your change

• Replace links pointing to vmware/harbor which then redirects back to goharbor/harbor

Why?

if vmware creates repo named harbor. this redirection will break and this link will not be redirected back to goharbor/harbor.

Issue being fixed

Fixes #(issue)

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/docs"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[chlins]

lgtm