Fix JSON syntax issues in theme.json examples.

[mrobit]

What?

This PR fixes two trailing commas in the JSON examples for the theme.json documentation. Pretty lame PR, but figured this couldn't hurt!

Why?

It's minor, but if anyone copies and pastes these examples, they'll have a JSON syntax issue.

How?

Deleting the trailing commas.

[github-actions]

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[github-actions]

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Kudos!

[fabiankaegy]

Thanks for your contribution @mrobit 🚀

[bph]

Label [Type] User Documentation is for change concering End users = Content creators and no-code site builder

The [Type] Developer Documentation is the label used for the plugin release to automattically create the changelog section "Documentation"