Add info about custom subdomain for this this project.

README.md

@@ -7,6 +7,6 @@ This is an umbrella project for centralizing access to various self-contained ed
 - **Community Contributions**: This project is open for contributions from the community. If you have a self-contained educational unit that you would like to share, please consider contributing it to this project. Read the [Contributors' Guide](https://github.com/evarga/edu-units/blob/main/CONTRIBUTING.md) for details.
 
 - **Independent Evolution**: Subprojects may evolve independently of their container website. This is particularly useful when the subprojects are maintained by different authors or teams (in case people decide to contribute their unit(s) to this project).
-- **Self-Referencing Property**: This project is itself an educational unit, showcasing how to organize and present subordinate educational materials in a structured manner. More specifically, technologies like Jekyll, GitHub Pages, and Markdown are used to create a website that lists all linked projects.
+- **Self-Referencing Property**: This project is itself an educational unit, showcasing how to organize and present subordinate educational materials in a structured manner. More specifically, technologies like Jekyll, GitHub Pages, and Markdown are used to create a website that lists all linked projects. The custom subdomain for this site was configured via the [dnsimple](https://dnsimple.com/r/fefeb14211521c) service.
 
 The GitHub Pages based website for this project contains a list of all the linked projects, along with a brief description and a link to the respective repository. The website is accessible by following the link displayed in the right sidebar of this repository.