Add link to appendix from error handling documentation

[cdalexndr]

Please add documentation for server.error properties.
There is no mention in Error Handling docs

[scottfrederick]

The server.error properties are documented in the Common Application Properties appendix: https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-application-properties.html#server-properties. It would be useful to link to these properties from the Error Handling section.

[mbhave]

Closing in favor of #24314.