Update Pagination example with naming conventions

Author: danicatalan

Diff for: rest-api-guidelines/execution/pagination.md

@@ -15,7 +15,7 @@ The Collection of Orders using the collection navigation link and `offset` and `
     "first": { "href": "/orders?limit=10" },
     "last": { "href": "/orders?offset=900&limit=10" }
   },
-  "total_count": 910,
+  "totalCount": 910,
   "_embedded": {
     "order": [
       { ... },