Add contributor

Author: elias-a

CONTRIBUTORS.md

@@ -37,6 +37,7 @@ We are certain the list is incomplete; please let one of us know by opening an [
 + Alex Herrera ([@aherrera1721](https://github.com/aherrera1721))
 + Michał Górny ([@mgorny](https://github.com/mgorny))
 + Ryder Johnson ([@UZ9](https://github.com/UZ9))
++ Elias Alstead ([@elias-a](https://github.com/elias-a))
 
 ## Full timeline of vpython development