update members (#55)

Author: zuhengxu

_data/members.yml

@@ -150,4 +150,13 @@
   photo: https://avatars.githubusercontent.com/u/5433119?v=4
   github: sunxd3
   institution: University of Cambridge
-  email: [email protected]
+  email: [email protected]
+
+- name: Zuheng(David) Xu
+  photo: https://zuhengxu.github.io/assets/img/profile.png
+  github: zuhengxu
+  institution: University of British Columbia
+  website: https://zuhengxu.github.io/
+  email: [email protected]
+  twitter: ZuhDav
+  linkedin: zuheng-david-xu-29825624b