Adding reference projects (#196)

Co-authored-by: Jacky Zhao <j.zhao2k19@gmail.com>

content/notes/showcase.md

@@ -14,6 +14,8 @@ Want to see what Quartz can do? Here are some cool community gardens :)
 - [Course notes for Information Technology Advanced Theory](https://a2itnotes.github.io/quartz/)
 - [Brandon Boswell's Garden](https://brandonkboswell.com)
 - [Siyang's Courtyard](https://siyangsun.github.io/courtyard/)
+- [Data Dictionary 🧠](https://glossary.airbyte.com/)
+- [sspaeti.com's Second Brain](https://brain.sspaeti.com/)
 - [oldwinterの数字花园](https://garden.oldwinter.top/)
 
 If you want to see your own on here, submit a [Pull Request adding yourself to this file](https://github.com/jackyzha0/quartz/blob/hugo/content/notes/showcase.md)!