Spring Boot Starter: adjust "OpenTelemetry starter" terminology

[chalin]

Originally posted by @jeanbisutti in https://github.com/open-telemetry/opentelemetry.io/issues/4563#issuecomment-2141257204

Spring Boot provides the possibilty to create starters: https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#using.build-systems.starters

The full name would be "OpenTelemetry Spring Boot starter". "OpenTelemetry starter" is shorter and could be understood as a "Spring Boot starter" in the context of Spring Boot applications.