springboot Link to correct factory in TomcatReactiveWebServerFactory's javadoc

Corrected constructor javadocs to link to the correct ConfigurableTomcatWebServerFactory implementation.

Comment From: wilkinsona

@j0rdanit0 Thank you very much for making your first contribution to Spring Boot. The changes are now in 2.1.x, 2.2.x, and master.

Comment From: j0rdanit0

I use Spring Boot almost every day, I'm honored to contribute in this very small way. Now that I understand how it works, maybe I'll be able to make more meaningful contributions in the future. :) Thank you!