Add further acknowledgements to introducing-metrics-in-innersource.md

See discussion on InnerSourceCommons#497

Author: spier

patterns/1-initial/introducing-metrics-in-innersource.md

@@ -115,3 +115,6 @@ Initial
 - [Aaron Stewart](https://github.com/a-a-ron/innersource-template-pluralsight/tree/master/metrics)
 - Wilson Mar
 - Addie Girouard
+- Alberto Pérez García-Plaza
+- Daniel Izquierdo Cortázar
+