Add salaheldin to MAINTAINERS.md (#1636)

A proud moment.

MAINTAINERS.md

@@ -6,3 +6,4 @@
 | Sean Young        | [@seanyoung](https://github.com/seanyoung) | seanyoung#0481 |
 | Lucas Steuernagel | [@LucasSte](https://github.com/LucasSte)  | LucasSte#2331  |
 | Cyrill Leutwiler  | [@xermicus](https://github.com/xermicus)  | kägifret#8095  |
+| Salaheldin Soliman| [@salaheldinsoliman](https://github.com/salaheldinsoliman) | salaheldinsoliman  |