Added @api tag for documentation

src/Spout/Writer/ODS/Writer.php

@@ -27,6 +27,7 @@ class Writer extends AbstractMultiSheetsWriter
      * Sets a custom temporary folder for creating intermediate files/folders.
      * This must be set before opening the writer.
      *
+     * @api
      * @param string $tempFolder Temporary folder where the files to create the ODS will be stored
      * @return Writer
      * @throws \Box\Spout\Writer\Exception\WriterAlreadyOpenedException If the writer was already opened