Give priority to ATOM to expose WebSub.
Hello, The ATOM feed contains the hub declaration for WebSub / PubSubHubbub, but the RSS / RDF / JSON versions do not. Currently, the ATOM version is declared last. RSS/ATOM clients typically pick whichever version comes first, and will thus not see the WebSub feature. I therefore suggest putting the ATOM version first, as it is more feature-rich than the other versions. Clients not compatible with ATOM would not pick it anyway due to the different type attribute. See same PR for Mastodon: https://github.com/tootsuite/mastodon/pull/9302 and WebSub tester https://websub.rocks/publisher