people: add John Horton Conway to peoplelist.json, johnhortonconway.json

The changes add John Horton Conway to the list of people in
peoplelist.json and create a new profile for him in johnhortonconway.json

This allows for the inclusion of information about John Horton Conway in
the application, such as his contributions, affiliations, and social
media links.

peoplelist.json

@@ -199,6 +199,10 @@
     {
       "displayname": "Nolan Berry",
       "filename": "nolanberry"
+    },
+    {
+      "displayname": "John Horton Conway",
+      "filename": "johnhortonconway"
     }
   ]
 }