Add `brand-teal` to color palette

[mscottford]

Use https://javisperez.github.io/tailwindcolorshades/?persian-green=22AF99 to create a brand-teal color.

This color could be used to create a header color for the CardWithHeader component on the /community page. See

website/src/pages/community.jsx

Lines 4 to 19 in 2d71c09

	export function CardWithHeader({title, children}) {
	return (
	<>
	<div className="divide-y divide-gray-200 overflow-hidden rounded-lg bg-white shadow my-4 mb-6">
	<div className="not-prose px-4 py-5 sm:px-6 bg-brand-yellow-400">
	<h3 className="text-base font-semibold leading-6 text-gray-900">
	{title}
	</h3>
	</div>
	<div className="px-4 py-0">
	{children}
	</div>
	</div>
	</>
	)
	}

.