Allow to show RSS posts and/or news donators/subs.

Example to use :

https://www.buymeacoffee.com/thomasbnt/index.rss (for all entries)

https://www.buymeacoffee.com/thomasbnt/posts/index.rss (only posts)

https://www.buymeacoffee.com/thomasbnt/coffee/index.rss (only donations)

https://www.buymeacoffee.com/thomasbnt/subs/index.rss (only subs)

https://www.buymeacoffee.com/thomasbnt/coffeeandsubs/index.rss (donators and subs)