- adds missing entry to the toc for middleware

[baywet]

follow up to #38

[learn-build-service-prod]

Learn Build status updates of commit 5670f27:

✅ Validation status: passed

File	Status	Preview URL	Details
OpenAPI/kiota/toc.yml	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit 9c8a6ea:

✅ Validation status: passed

File	Status	Preview URL	Details
OpenAPI/kiota/index.yml	✅Succeeded
OpenAPI/kiota/toc.yml	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel