[skip ci] Add comment for setIndexParams (#13530)

Signed-off-by: bigsheeper <yihao.dai@zilliz.com>

internal/querynode/index_info.go

@@ -60,6 +60,7 @@ func (info *indexInfo) setIndexPaths(paths []string) {
 	info.indexPaths = paths
 }
 
+// setIndexParams sets the params of index, such as indexType, metricType and so on
 func (info *indexInfo) setIndexParams(params map[string]string) {
 	info.indexParams = params
 }