add codespell action (#18818)

Original work here, #18474,  refixed and updated.

cmd/erasure-object_test.go

@@ -799,7 +799,7 @@ func TestPutObjectNoQuorumSmall(t *testing.T) {
 }
 
 // Test PutObject twice, one small and another bigger
-// than small data thresold and checks reading them again
+// than small data threshold and checks reading them again
 func TestPutObjectSmallInlineData(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()