Document maintenance mode and recommended migrations

[OlgaMaciaszek]

[OlgaMaciaszek]

Thanks @ch4mpy. We're planning to be adding some starters/autoconfigruations for @HttpExchange in Spring Boot (it's now a task in progress: spring-projects/spring-boot#31337). Please keep an eye on that and once that's merged see if you'd like to contribute any additional add-ons.

[ch4mpy]

@OlgaMaciaszek thks for the useful link. I delete my previous post because what I do is clearly behind httpexchange-spring-boot-starter (referenced in the thread you linked) and probably not as useful as what the official Spring support will be.