Update app-runtime-platform.md to include Marc Paquette as a Diego Approver

Diego Approver

cloudfoundry/bbs#64
cloudfoundry/bbs#68

cloudfoundry/diego-dockerfiles@3aa03b8
cloudfoundry/diego-dockerfiles@77dccfa
cloudfoundry/diego-dockerfiles@c69911c
cloudfoundry/diego-dockerfiles@df0aed2

cloudfoundry/diego-release@05dcaba
cloudfoundry/diego-release@390d5d7
cloudfoundry/diego-release@4d5e6a1
cloudfoundry/diego-release@5158007
cloudfoundry/diego-release#740

cloudfoundry/docs-cloudfoundry-concepts#181

cloudfoundry/dontpanic#39

cloudfoundry/executor#76
cloudfoundry/executor#80

cloudfoundry/grace#3

cloudfoundry/healthchecker-release#2

cloudfoundry/wg-app-platform-runtime-ci@03fa33d
cloudfoundry/wg-app-platform-runtime-ci@3affeda

PR Reviews:
cloudfoundry/buildpackapplifecycle#55
cloudfoundry/cacheddownloader#18
cloudfoundry/diego-release#689
cloudfoundry/diego-release#690
cloudfoundry/diego-release#704
cloudfoundry/diego-release#728

Author: Marc Paquette

toc/working-groups/app-runtime-platform.md

@@ -66,6 +66,8 @@ areas:
     github: winkingturtle-vmw
   - name: David Sabeti
     github: dsabeti
+  - name: Marc Paquette
+    github: marcpaquette
   reviewers:
   - name: Plamen Doychev
     github: PlamenDoychev