Add comment for WriteExtractedString

runtime.go

@@ -782,6 +782,9 @@ func ToGoHTML(ctx context.Context, c Component) (s template.HTML, err error) {
 	return
 }
 
+// WriteExtractedString is used when rendering templates in development mode.
+// the generator would have written non-go code to the _templ.txt file, which
+// is then read by this function and written to the output.
 func WriteExtractedString(w *bytes.Buffer, lineNum int) error {
 	_, path, _, _ := runtime.Caller(1)
 	if !strings.HasSuffix(path, "_templ.go") {