Update FUNDING.yml

Author: Relequestual

.github/FUNDING.yml

@@ -6,4 +6,4 @@ open_collective: json-schema
 ko_fi: relequestual
 tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
 community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
-custom: # Replace with a single custom sponsorship URL
+custom: https://buymeacoffee.com/relequestual