Add ability to expand table of contents by default

We’re frequently referencing our tables of content. Having to click to open the TOC every time we go into a card is repetitive and frustrating, especially when the TOC is there to help make navigation easier. We’d like the ability to have all TOCs open by default. There isn’t really a reason not to - it doesn’t change how the card content appears on screen, and there’s already plenty of white space set aside for this ability.