Docs: typo in publish_scope url in Middlewares

[kurrbanov]

Go to: https://faststream.ag2.ai/latest/getting-started/middlewares/#basic-middlewares-flow

Try to click on 'publish_scope'.

Current result: https://faststream.ag2.ai/latest/getting-started/middlewares/#important-information-about-publishscope

Expected result: https://faststream.ag2.ai/latest/getting-started/middlewares/#important-information-about-publish_scope