Fix `description` for `seo` option in #1311.
Fix `description` for `seo` option in #1311.

If `seo` is true main site description will be passed by `config.subtitle` option in main Hexo config.
But, there is duplicate of description by sidebar code (author & description).
So, we will separate main site description and author description and u may use `theme.signature` option for author description (signature).
mchsinx/hexo-theme-next