Fix some typos in documentation
Fix some typos in documentation

In particular:

- add missing `new` operator
- ensure that `RouteDefinitionLocators` is properly formatted in the "Configuration" section
- "Normwal" -> "Normal"
- remove extra "`"

spring-cloud-incubator/spring-cloud-gateway,spring-cloud-incubator/spring-cloud-gateway,spencergibb/spring-cloud-gateway,spencergibb/spring-cloud-gateway