[skip ci] Add comment for newCollection (#9366)

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

internal/querynode/collection.go

@@ -200,6 +200,7 @@ func (c *Collection) getLoadType() loadType {
 	return c.loadType
 }
 
+// newCollection returns a new Collection
 func newCollection(collectionID UniqueID, schema *schemapb.CollectionSchema) *Collection {
 	/*
 		CCollection