Demonstrate how to use CO2.js in different runtimes

[fershad]

Is your feature request related to a problem? Please describe.
Currently, the demos and tutorials show how to install and use CO2.js in a NodeJS environment. However, there are now more JavaScript runtimes available for developers to use and deploy to. Two of the more popular ones are Deno, Bun.

It would be good to have documentation showing how to install & use CO2.js in both of these JS runtimes.

Describe the solution you'd like

• One the Installation page, add sections showing how to install CO2.js in Deno and Bun.
• Adjust the Getting started: NodeJS page to be more generic and include Deno and Bun.