Polish

See gh-4953
Closes gh-5745

Author: mbenson

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -682,7 +682,7 @@ profile, and it would have to be explicitly reset in all other profiles as neces
 ----
 
 Spring profiles designated using the "spring.profiles" element may optionally be negated
-using the {@code !} character. If both negated and non-negated profiles are specified for
+using the `!` character. If both negated and non-negated profiles are specified for
 a single document, at least one non-negated profile must match and no negated profiles
 may match.