Allow users to support you with Bitcoin Cash

Hello DarkReader peoples,

Recently another dev, @EchterAgo introduced me to DarkReader. I have been using it every day since then and it's such a huge improvement for someone like me that gets headaches from bright lights. I want to support your development so I made an account on OpenCollective. However they are limited to credit cards, paypal and bank transfers which do not work for me. Could I beg you to add a Bitcoin Cash donation method so that I can support you?

The easiest way is just to put a single receiving address / QR code (edit - you can get that with [Electron Cash](https://electroncash.org/)). If you want to do some kind of integration, there are a number of options (https://business.bitcoincash.com/merchant-solutions).

In any case, thank you for DarkReader. It is a serious quality of life improvement for people like me.

未指定文件或测试。首先检查 Dark Reader 网站现有的捐赠或支持内容以及 OpenCollective 的支付方式，然后确定 Bitcoin Cash 地址或 QR code 应该放在哪里。完成标准是新的捐赠方式得到清晰呈现，并且其链接或支付详情有效。

由索引模型根据 Issue 内容生成。