[skip e2e]Add comments to conf adapter file (#14760)

Signed-off-by: jingkl <jingjing.jia@zilliz.com>

internal/util/indexparamcheck/conf_adapter.go

@@ -298,6 +298,7 @@ func newBinIVFConfAdapter() *BinIVFConfAdapter {
 type NSGConfAdapter struct {
 }
 
+// CheckTrain checks if a nsg index can be built with specific parameters.
 func (adapter *NSGConfAdapter) CheckTrain(params map[string]string) bool {
 	if !CheckStrByValues(params, Metric, METRICS) {
 		return false