Fix incorrect link in kafka.adoc

[chanhyeong]

I think the document about kafka might be moved from features to messaging, but there is still an old link.

[snicoll]

@chanhyeong tanks for the PR but I believe that the link is correct. The features at the beginning is an old artifact from a previous version but handled properly as we rewrite anchors.

Did you notice a version of the Spring Boot docs where the link isn't working? If that's the case, please share a link to it and we can investigate.

Irrespective of this, I don't think this change is correct.

[chanhyeong]

@snicoll

I think it will be fixed after deploying 4c5cb77.

I found this in current version (2.6.6). (https://docs.spring.io/spring-boot/docs/current/reference/html/index.html)
Currently, it works in single HTML page but doesn't work in messaging.
There are difference sentences too.

single HTML page

messaging

[snicoll]

@chanhyeong Sorry about that. I thought anchor rewrite was handling it, especially after having looked at the current doc. I looked for the single page version though. Going forward, please provide the link to the broken link please.

kafka is incorrect as I've mentioned but I'd like to give you the contribution. Thanks for getting back to us!

[snicoll]

@chanhyeong thank you for making your first contribution to Spring Boot.