Add comment to otelVersion mentioning that it's auto-updated (#410)

Author: Mateusz Rzeszutek

dependencyManagement/build.gradle.kts

@@ -11,6 +11,8 @@ data class DependencySet(val group: String, val version: String, val modules: Li
 val dependencyVersions = hashMapOf<String, String>()
 rootProject.extra["versions"] = dependencyVersions
 
+// this variable is updated by opentelemetry-java-instrumentation release process, if you change its
+// name make sure that the instrumentation repo also reflects these changes
 val otelVersion = "1.16.0"
 
 val DEPENDENCY_BOMS = listOf(