update members' info

Author: yuhattor

data/members.yaml

@@ -10,7 +10,7 @@ members:
 
   - name: "Fei Wan"
     role: "Member"
-    area: "China"
+    area: "United States of America"
 
   - name: "Jerry Tan"
     role: "Member"
@@ -48,6 +48,10 @@ members:
     role: "Member"
     area: "Germany"
 
+  - name: "Johannes Tigges"
+    role: "Member"
+    area: "Germany"
+
   - name: "Tom Sadler"
     role: "Treasurer"
     area: "United Kingdom"