Fix anchor in link to "Web on Reactive Stack" chapter

[shitian9]

handle <<web-reactive.adoc#spring-webflux(Anchor doesn't resolve), Web Reactive>>

[sbrannen]

For the current documentation, the "Web Reactive" link works fine.

In light of that, I am closing this issue.

If you are reporting something different, please provide additional input.

[sbrannen]

For the current documentation, the "Web Reactive" link works fine.

Actually, I now see the point you were making.

The link effectively works fine, since it goes to the beginning on that chapter, which is the intent.

However, you are correct: the #spring-webflux anchor does not exist and should be replaced with #spring-web-reactive.

In light of that, I am reopening this PR.

[sbrannen]

This has been merged into main and backported to 5.3.x.

Thanks