Add entry to "A length-indexed Vector in Rust"

I stumbled on this post about a technique to construct a kind of vector whose size is a compile-time constant.

Author: guilleme-90

draft/2025-02-19-this-week-in-rust.md

@@ -43,6 +43,7 @@ and just ask the editors to select the category.
 
 ### Rust Walkthroughs
 * [Rust in Audio: Collections](https://www.youtube.com/watch?v=wFiMtYtHss8&t=11s)
+* [A length-indexed Vector in Rust](https://rvarago.github.io/a-length-indexed-vector-in-rust/)
 
 ### Research