I have a website hosted on netlify: https://eyasugc.netlify.app/. However, I also would like to add my github pages domain name, i.e., eyaget.github.io, as a custom domain name. When I tried to add this custom domain, I received the following message: " github.io is already registered. If you registered this domain name through a different registrar, select Add domain to begin delegating it to Netlify". When I click the “Add domain” button, I received the following message: “Another site is already using this domain. Domains must be unique across Netlify. Currently another site is using this domain. If you don’t know which site, please contact support for guidance”. Another site is not using my github domian, i.e., eyaget.github.io. I am not sure why netlify is indicating that it is being used by another site. Please help to check the matter.