{% set tree = toctree(titles_only=true, maxdepth=2, collapse=False, includehidden=true) %}

{{ tree
    | replace(' class="current"', '')
    | replace('<ul>', '<ul class="sub">')
    | replace('<li class="toctree-l">', '<li class="sub-menu">')
    | replace('<li class="toctree-l1">', '<li class="sub-menu">')
    | replace('</a><ul class="sub">', '<div class="arrow fa fa-angle-right"></div></a><ul class="sub">') }}