More generic language and download button at top

[jgresham]

• New Download button at the top, that auto detects the user's OS and Arch if possible
• Change language to be less Ethereum specific
• Change application screenshot to the new one at the figma link (I think the resolution is the same as the old screenshot)

Figma: https://www.figma.com/file/wB9IcBJsqefuWTr8z5Ym43/NiceNode-Website-UI?type=design&node-id=1061%3A1697&mode=design&t=hQBqhmA1qsucFJ7I-1