Add series prefix

Author: jdrouet

draft/2025-03-19-this-week-in-rust.md

@@ -41,7 +41,7 @@ and just ask the editors to select the category.
 
 ### Rust Walkthroughs
 
-* [Building a search engine from scratch](https://jdrouet.github.io/posts/202503161800-search-engine-intro/)
+* [series] [Building a search engine from scratch](https://jdrouet.github.io/posts/202503161800-search-engine-intro/)
 
 ### Research