[Task] Add examples for documentation

[Saoski]

Describe the task

New example payloads should be added to the asyncapi V1 documentation

Why this task

Currently, empty or very minimal json objects are used as default examples. Some more specific json objects should be used to give game developers a more understandable example as to what data they should put in their HTTP requests.

Todo List

• Add examples to the following operations
  • upsert_save_data
  • get_save_data
  • insert_leaderboard_entry
  • get_leaderboard

Additional context

You can copy the yaml file into Asyncapi Studio to easily see the changes you make