Documentation for setting up body filter with Spring Boot Auto-configuration

[mindhaq]

The information of #298 should be part of the README, including necessary imports. It's possible to find it in closed issues, but that's not ideal.

A link to LogbookAutoConfiguration is also helpful to see what's possible outside application.yml.

[whiskeysierra]

https://github.com/zalando/logbook#spring-boot-starter already contains most pieces but should be extended.