Add Benjie to July 2020 WG (graphql#448)

Author: benjie

agendas/2020-07-02.md

@@ -39,6 +39,7 @@ agenda, edit this file.*
 | Andi Marek              | GraphQL-Java                    | Sydney, Australien
 | Ivan Goncharov           | graphql-js               | Lviv, Ukraine
 | Morris Matsa             | IBM                      | Boston, US
+| Benjie Gillam ✏          | Graphile                 | Southampton, UK
 | *ADD YOUR NAME ABOVE TO ATTEND*