I’ve checked both sitemaps and they’re accessible and valid. For automatic validation, I used an XML Sitemap Validator.
Small websites with fewer than 100 URLs, don’t need a sitemap. Here’s an explanation.
Discourse Sitemap Plugin
In case you haven’t used the Discourse Sitemap Plugin, it adds a sitemap.xml to your Discourse instance.
Submitting your sitemap to Google
As a quick reference, here are the Google guidelines to build and submit a sitemap