docs(advisors): Clarify to only return packages with findings

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

Author: sschuberth

plugins/advisors/api/src/main/kotlin/AdviceProvider.kt

@@ -30,7 +30,8 @@ import org.ossreviewtoolkit.plugins.api.Plugin
  */
 interface AdviceProvider : Plugin {
     /**
-     * For a given set of [Package]s, retrieve findings and return a map that associates packages with [AdvisorResult]s.
+     * For a given set of [packages], retrieve findings and return a map of only those packages that actually have
+     * findings associated with an [AdvisorResult].
      */
     suspend fun retrievePackageFindings(packages: Set<Package>): Map<Package, AdvisorResult>