Add tabbed install block

[maxelkins]

Summary

• Add tabbed install block on the homepage
• Follows w3c implementation example

Note

I suspect most people will want to use brew? Since first tab and slightly hidden curl manual option.
...Hmm wonder if we could prioritise curl option depending on UA?

No worries if we'd prefer to surface both options on the page, the updated styles of the code block would still be useful.

Chosen not to create a more generalise "tab" component for now since this is the only place its used.

[grega]

Very nice 👍

Brew is definitely the better first choice, and can be used on either macOS or Linux, and probably WSL2 on Windows. cURL is always a solid backup option for those who'd rather not use a package manager (I assume a pretty small minority).

[maxelkins]

Great!

Forgot need to update the tests, will do that 👍

[maxelkins]

g2g

[grega]

I'll hit the Actions website deploy button now so it'll be published right away...