add entry for the new input

Author: v1v

README.md

@@ -14,10 +14,23 @@ This action outputs Github Action workflows and jobs details to OTLP via gRPC.
 
 **Optional** Additional header configuration to pass in as metadata to the gRPC connection.
 
+## `repo-token`
+
+**Optional** Token to use to authorize access to private repositories. Typically the `GITHUB_TOKEN` secret, with `checks:read` access.
+
 ## Example usage
 
 ```
 uses: codeboten/github-action-to-otlp@v1
 with:
   endpoint: 'grpc.otlpendpoint.io:443'
 ```
+
+## Example usage in a private repository
+
+```
+uses: codeboten/github-action-to-otlp@v1
+with:
+  endpoint: 'grpc.otlpendpoint.io:443'
+  repo-token: ${{ secrets.GITHUB_TOKEN }}
+```