Fix contribution issue sentence

[jsoref]

Description

The contribution page bullet didn't make sense as is. I considered filing a bug, but tbh because of the sentence as is, I can't tell if I needed to or not. I've decided that I probably don't need to, and since the fix is so short, it feels like just offering it is better than filing an issue on the point.

Submitter Checklist

See the contribution guide for more details.

Note: I read the contributing guide, none of the changes I'm making involve code, which is why I've removed the checkboxes. And ... well, the contributing guide is confusing. But, I'm trying :-)

Reviewer Notes

• The code flow looks good.
• Unit tests and or integration tests added.

Release Notes

Describe any changes here so maintainer can include it in the release notes, or delete this block.

Examples of user facing changes:
- Skaffold config changes like
  e.g. "Add buildArgs to `Kustomize` deployer skaffold config."
- Bug fixes
  e.g. "Improve skaffold init behaviour when tags are used in manifests"
- Any changes in skaffold behavior
  e.g. "Artiface cachine is turned on by default."