Update developer document on dependency updates

[janosi]

What this PR does / why we need it:

The way how dependencies in /vendor can be updated has changed, so we shall update the documentation to reflect that.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

How Has This Been Tested?

I run go get <mypackage> and then make dep-ensure and the new dependency got into the /vendor folder and the compilation process was successful.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

[k8s-ci-robot]

Hi @janosi. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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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.

[aledbf]

/ok-to-test

[aledbf]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, janosi

The full list of commands accepted by this bot can be found here.

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• OWNERS [aledbf]

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[aledbf]

@janosi thanks!

[codecov-io]

Codecov Report

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The diff coverage is n/a.

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