[BUGFIX] Set addSubAggregation to protected method

- fix method documentation

Author: johannessteu

Classes/Flowpack/ElasticSearch/ContentRepositoryAdaptor/Eel/ElasticSearchQueryBuilder.php

@@ -436,7 +436,8 @@ public function fieldBasedAggregation($name, $field, $type = "terms", $parentPat
 	 *
 	 * aggregationDefinition = TYPO3.TypoScript:RawArray {
 	 *   terms = TYPO3.TypoScript:RawArray {
-	 *   field = "color"
+	 *     field = "color"
+	 *   }
 	 * }
 	 *
 	 * nodes = ${Search....aggregation("color", this.aggregationDefinition).execute()}
@@ -475,7 +476,7 @@ public function aggregation($name, array $aggregationDefinition, $parentPath = N
 	 * @return $this
 	 * @throws QueryBuildingException
 	 */
-	public function addSubAggregation($parentPath, $name, $aggregationConfiguration) {
+	protected function addSubAggregation($parentPath, $name, $aggregationConfiguration) {
 		// Find the parentPath
 		$path =& $this->request['aggregations'];