Modify acknowledgement by adding PPE team

Author: therealthaibinh

src/penn_chime/locales/en.yml

@@ -92,6 +92,11 @@ en:
   presentation-references-acknowledgements-text: |+
     * AHA Webinar, Feb 26, James Lawler, MD, an associate professor University of Nebraska Medical Center, What Healthcare Leaders Need To Know: Preparing for the COVID-19
     * We would like to recognize the valuable assistance in consultation and review of model assumptions by Michael Z. Levy, PhD, Associate Professor of Epidemiology, Department of Biostatistics, Epidemiology and Informatics at the Perelman School of Medicine
+    * The PPE tool was developed by Kristian Lum, James Johndrow, April Cardone, Barry Fuchs, Cody E. Cotner,
+    Olivia Jew, Ravi B. Parikh, Gary E. Weissman, Christian Terwiesch, and Kevin G. Volpp from various departments across
+    the University of Pennsylvania (Department of Computer and
+    Information Science; Wharton School; Perelman School of Medicine; Center for Health Incentives and Behavioral
+    Economics) and Penn Medicine (Hospital of the University of Pennsylvania).
     * Finally we'd like to thank [Code for Philly](https://codeforphilly.org/) and the many members of the open-source community that [contributed](https://github.com/CodeForPhilly/chime/graphs/contributors) to this project.
   presentation-copyright: "© 2020, The Trustees of the University of Pennsylvania"
   presentation-download: |+