Fix JSON syntax error in BatchCheck documentation examples

Description

The BatchCheckRequest example in the BatchCheck API documentation contains invalid JSON due to missing commas after the object field in the tuple_key objects.

Issue Details

In the BatchCheck documentation, the example JSON is missing commas:

Current (invalid):

"tuple_key": {
  "object": "document:2021-budget"
  "relation": "reader",
  "user": "user:anne",
}

Expected (valid):

"tuple_key": {
  "object": "document:2021-budget",
  "relation": "reader",
  "user": "user:anne",
}

This occurs in both tuple examples in the BatchCheckRequest section.

Context

This issue was identified during review of https://github.com/openfga/dotnet-sdk/pull/120. The generated documentation in the .NET SDK reflects the upstream API specification, so the fix needs to be applied in this repository.

See comment: https://github.com/openfga/dotnet-sdk/pull/120#discussion_r2380256977

Requested by

@rhamzeh

Search this repository for the BatchCheckRequest section and locate both tuple examples in the BatchCheck documentation. Correct the missing commas after each object value, then verify that both examples are valid JSON and match the expected form described in the issue.