Add `<wbr>` to whitelist

[Mottie]

Please include the <wbr> element in the whitelist.

It is useful when I need a table to not overly stretch the width of a column. So, I can then use markdown instead of adding a complete table in HTML.

Is this repo still maintained? GitHub markup points here, but there doesn't seem to be a lot of activity.

[Mottie]

Hmm, nevermind, I can add ­ (which adds a dash at the break) or ​ (zero-width white-space). They won't work inside of code blocks, unless you manually wrap the block with <code> or <pre> HTML.