Make explicit that you can use ipfs cid format to convert both ways

[dannyob]

It took me a moment to realise that this was possible, so wanted to save that moment for future generations of IPFS newbies.

Describe your changes

Just an extra line in the docs explicitly showing how to use ipfs cid format -v 0.

Files changed

• docs/concepts/content-addressing.md

Does this update depend on any other PRs?

nope!

Checklist before requesting a review

• Passing the beta version of the Check Markdown links for modified files check. Action results can be viewed here.

Checklist before merging

• Passing all required checks (The beta Check Markdown links for modified files check is not required)

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