README external beta testers

Signed-off-by: Axel Gomez <92367498+axgmz@users.noreply.github.com>

README.md

@@ -671,6 +671,9 @@ Distributed under the GNU Affero General Public License v3.0. See `LICENSE` for
 
 - Olaia Anton, Zakarya Benayad, Miguel de la Puente, Axel Gomez
 - Oscar Gayraud, Pierre Girard, Anne Milet
+- Meritxell Malagarriga Perez, Adrián García
+- Elizabeth R. Bartlett, Ward H. Thompson
+- Hadi Dinpajooh
 
 ### Atomsk ###