Add graphapi to the list of GraphQL services. (#1375)

We are excited about the opportunity to be part of this list. Thanks!

Author: Jeansse

src/content/code/services/graphapi.md

@@ -0,0 +1,6 @@
+---
+name: graphapi® 
+description: graphapi® is a secure low-code GraphQL-as-a-service platform. Based on the input data model, it auto-generates the GraphQL schema, all resolvers, and the database stack. Additionally, it provides a user interface allowing teams to manage their data. For more information, go to https://graphapi.com.
+url: https://graphapi.com/docs
+github: graphapi-io/resources
+---