Consider mentioning OpenTelemetry Spring Boot starter in reference manual

[vpavic]

It would be helpful if OpenTelemetry Support section of reference manual would mention OpenTelemetry's own Spring Boot starter (see #40339) as another way of configuring OpenTelemetry in Spring Boot applications as it has several advantages:

• provides instrumentation support for large number of popular libraries
• makes it easier to use the latest version of OpenTelemetry
• doesn't require Actuator

[wilkinsona]

Thanks for the suggestion. This isn't the sort of thing that we typically include in the reference documentation, preferring to focus on what Boot itself offers. The list of third-party starters is the right place for this.