Gatsby: chore(www): Use react-icons' discord icon instead of our custom one

[tesseralis]

Description

I don't see why we're using a custom discord icon component instead of the one that react-icons has. I'm guessing we included it before react-icons added it in, but we should be able to switch it out now.

[HarryFray]

@tesseralis looking into it. This might be my first contribution to open source! 😅

Looks like the Icon is only used in one place.

[tesseralis]

@HarryFray go ahead!

[fk]

I'm guessing we included it before react-icons added it in

Yep! www is still using react-icons v2
https://github.com/gatsbyjs/gatsby/blob/ff5458502473b4f50febc717266ce039ac26a93f/www/package.json#L89
The version of Font Awesome icons it includes didn't have it: https://react-icons.github.io/react-icons/fa.html

but we should be able to switch it out now.

💯https://react-icons.netlify.com/#/icons/fa