Bitcoin QR graphic no longer displayed; other suggestions

[lah7]

A new member of the community voiced concerns and improvements for the Bitcoin section on the Funding page:

• https://ubuntu-mate.community/t/i-love-the-os-you-need-to-update-the-donation-page-with-a-bitcoin-qr-and-lightning-qr/28748

The main issue is that the QR graphic is no longer displayed. The image link for chart.googleapis.com/chart is dead.