Remove "chin" in admonition blocks of reference documentation
Remove "chin" in admonition blocks of reference documentation

Originally contributed by @olivergierke via
spring-projects/spring-framework#1520. This commit is based on
the spring.css generated from the SASS original source, see
bclozel/asciidoctor-stylesheet-factory#1.

spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework