Add links to Copper integrations

[tusharsoni]

Please make sure all the requirements are satisfied, otherwise the PR could be closed without further notice.

Checklist

• [x] Title as described.
• [x] Make sure you put things in the right category.
• [x] The description of your item should be a sentence with less than 24 words.
• [x] Avoid using links and parentheses in description.
• [x] Omit unnecessary words already provided in the context (e.g. for Vite, a Vite plugin).
• [x] Use proper case for terms (e.g. GitHub, TypeScript, ESLint, etc.)
• [x] When mentioning tools, omit versions whenever possible (e.g. use TypeScript instead of TypeScript 4.x, but keep Vue 2 and Vue 3 as they're incompatible).
• [x] When mentioning package names, use quotes whenever possible.
• [x] Always add your items to the end of a list.

Plugins/Tools

• [x] The plugin/tool is working with Vite 2.x and onward.
• [x] The project is Open Source.
• [x] The project follows the Vite Plugins Conventions.
• [x] The plugin uses Vite-specific hooks and can't be implemented as a Compatible Rollup Plugin.
• [x] The repo should be at least 30 days old.
• [x] The documentation is in English.
• [x] The project is active and maintained (inactive projects for longer 6 months will be removed without further notice).
• [x] The project accepts contributions.
• [x] Not a commercial product.

Starter Templates

• [ ] The starter template is working with Vite 2.x and onward.
• [ ] The documentation is in English.
• [ ] The starter template most provide enough instructions / documentation about how to start up and what's is included.
• [ ] A screenshot or a live demo should be included.
• [ ] The repo should be at least 30 days old.
• [ ] Should be differentiable from the existing starter templates.

Apps/Websites

• [x] The website is available without errors and load in a reasonable amount of time.
• [x] The website must be Open Source and showing it's using Vite intensively.
• [x] The website is original and not too simple. For that reason, blogs and simple landing pages are rejected.

[Scrum]

I'm not sure if it's worth posting utility software here, even if it can work through Vite.

@antfu @patak-dev What do you think about this ?

[tusharsoni]

I don't think I'd categorize Copper as "utility software". It's a backend framework written in Go and I'm adding its integration with ViteJS under the Backend Integrations section.

For example -

- [React](https://docs.gocopper.dev/getting-started/create-project/react) - Integration for [Copper](https://gocopper.dev/).

creates a project using Copper + React + ViteJS

- [React + TailwindCSS](https://docs.gocopper.dev/getting-started/create-project/react-+-tailwind) - Integration for [Copper](https://gocopper.dev/).

creates a project using Copper + React + Tailwind + ViteJS