Add rollup-plugin-geojson

[n370]

Awesome Contribution Checklist:

• [x] I have read, and re-read the Contributing Guidelines
• [x] I have searched to ensure the suggested item doesn't exist on this list
• [x] This PR contains only one item

Please Provide a Link A Repository for Your Addition

https://github.com/n370/rollup-plugin-geojson

Please Describe Your Addition

Add a new plugin to the "other file imports" section. The new addition refers to a plugin that helps reading GeoJSON files.

[shellscape]

Sorry for the delay in reviewing your PR. Thanks for opening it.

[n370]

No prob @shellscape! Thank you!