// move the languages to the sidebar.
const languages = [...document.querySelectorAll('#p-lang-btn .interlanguage-link a')]
    .map(a => {
        a = a.cloneNode(true);
        const li = document.createElement('li');
        li.classList.add('vector-toc-list-item', 'vector-toc-level-1');
        li.append(a);
        return li;
    });

const toc = document.querySelector('.vector-toc-contents');
const div = document.createElement('div');
div.append(document.createElement('hr'));
div.append(...languages)
toc.append(div);