Suggestion to add WebApp manifest in reactjs.org

[saurabhdaware]

If we allow users to Add to homescreen the https://reactjs.org I think it would be helpful for people who want to have react docs on their homescreen and it would allow them to easily access the docs anytime they want.
Along with this we can even set the theme color for URL bar.

we can add gatsby-plugin-manifest to achieve this.

Edit: If you guys are planning to implment it I would love to work on this. It would be my first contribution here