fix(jsonld): update jsonld doc remarks; add return type

[collinwu]

Description

I leveraged this plugin for a project recently and noticed the general <JsonLd> component's documentation referenced the wrong prop, item instead of the expected prop, json

I added the imports and some additional code to hopefully make the example more clear. An ESLint complaint about the return type missing prompted me to add JSX.Element to the src file as well.

Checklist

• [x] I have read the contributing document.
• [x] My code follows the code style of this project and yarn fix runs successfully.
• [x] I have run yarn api:generate and updated the README documentation where necessary.
• [ ] New code is unit tested and all current tests pass when running yarn test && yarn test:e2e.

[github-actions[bot]]

:tada: This PR is included in version 1.8.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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