fixing typo in ceph-object-store-crd.md

[adippl]

Example cephobjectstore uses wrong field name for "dnsNames".

Checklist:

• [ ] Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• [ ] Reviewed the developer guide on Submitting a Pull Request
• [ ] Pending release notes updated with breaking and/or notable changes for the next minor release.
• [ ] Documentation has been updated, if necessary.
• [ ] Unit tests have been added, if necessary.
• [ ] Integration tests have been added, if necessary.

[parth-gr]

please update the commit message with this format https://rook.io/docs/rook/latest-release/Contributing/development-flow/#commit-structure

Just use, git commit -s --amend and update with the above format

[adippl]

I've added docs tag to commit title. Is this commit message fine?