Clarify that auto-configured OpenTelemetry Resource behaviour

The documentation does not describe that exposing a Resource bean,
will prevent the property from being able to provide attributes
(unless the newly exposed Resource bean, implements it).

Signed-off-by: Jakob Wanger <jakobwanger@gmail.com>

See gh-39509

spring-boot-project/spring-boot-docs/src/docs/asciidoc/actuator/observability.adoc

@@ -80,7 +80,7 @@ Spring Boot's actuator module includes basic support for https://opentelemetry.i
 
 It provides a bean of type `OpenTelemetry`, and if there are beans of type `SdkTracerProvider`, `ContextPropagators`, `SdkLoggerProvider` or `SdkMeterProvider` in the application context, they automatically get registered.
 Additionally, it provides a `Resource` bean.
-The attributes of the `Resource` can be configured via the configprop:management.opentelemetry.resource-attributes[] configuration property.
+The attributes of the `Resource` can be configured via the configprop:management.opentelemetry.resource-attributes[] configuration property if you have not defined and exposed your own Resource bean.
 
 NOTE: Spring Boot does not provide auto-configuration for OpenTelemetry metrics or logging.
 OpenTelemetry tracing is only auto-configured when used together with <<actuator#actuator.micrometer-tracing, Micrometer Tracing>>.