Fix typos in actuator docs for "when_authorized"

[t0r0X]

This PR fixes two typos in documentation of actuator health endpoints:
"Spring Boot > Reference > Production-ready Features > Endpoints"

https://docs.spring.io/spring-boot/reference/actuator/endpoints.html#actuator.endpoints.health

Wrong: when-authorized
Correct: when_authorized

[philwebb]

Thanks, but we prefer kebab case in properties and both of those should work in that form.

[t0r0X]

I did know that kebab-case is preferred for properties names, does this also apply to properties values?
The PR is about the value of property management.endpoint.health.show-details, not the name. Its own documentation says:

Values:
    never:           ...
    when_authorized: ...
    always:          ...

Also please note that in this section https://docs.spring.io/spring-boot/reference/actuator/endpoints.html#actuator.endpoints.sanitization there are already two usages of the enum value, but with upper case: show-values: WHEN_AUTHORIZED (backed by enum org.springframework.boot.actuate.endpoint.Show)

[philwebb]

Yes, we generally use it for both. That's the format used in the configuration properties metadata file. Thanks for pointing out the issue with the "Sanitize Sensitive Values" section, I've fixed that in #42702