feat(toc): seek anchor id from parent nodes when target is not available
feat(toc): seek anchor id from parent nodes when target is not available

Signed-off-by: Richard Lea <5e20e57f18b15612bae274c2aef7dc395ee6b2a1@zoho.com>

kywk/hexi,hexojs/hexo,ppker/hexo,hexojs/hexo,ppker/hexo,kywk/hexi