Where does `wp db export` mention `-`?  There is general mention of it in the definition of the `<file>` option in the class phpDoc:

```
 * <file>
 * : The name of the SQL file for import/export. If '-', then inputs from STDIN and outputs to STDOUT. If omitted, it will be '{dbname}.sql'.
```

The `export` command just has:

```php

	/**
	 * Exports the database using mysqldump.
	 *
	 * @alias dump
	 *
	 * @synopsis [<file>]
	 */
```

Do you want `-` noted explicitly in the comment block for both the `export` and `import` methods?