feat: adds line item example for cost API

Author: thli-openai

authors.yaml

@@ -241,4 +241,9 @@ ted-at-openai:
 MikeHeaton:
   name: "Mike Heaton"
   website: "https://github.com/MikeHeaton"
-  avatar: "https://avatars.githubusercontent.com/u/11911723?v=4"
+  avatar: "https://avatars.githubusercontent.com/u/11911723?v=4"
+
+thli-openai:
+  name: "Thomas Li"
+  website: "https://www.linkedin.com/in/thli/"
+  avatar: "https://avatars.githubusercontent.com/u/189043632?v=4"