Update acqknowledgements in footer

Author: Eric Smyth

src/chime_dash/app/templates/en/footer.md

@@ -2,5 +2,6 @@
 
 * 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
+* 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.
 
 © 2020, The Trustees of the University of Pennsylvania