Edit comment modal HTML markup issue

[Dennis Smink]

PR #101 described how to edit own comments, this is perfect, however:

When having HTML, it doesn't actually render the HTML, might be nice to render it and also put a prose class on it.

Press the "Edit" button for Fodderstompf here: https://roadmap.ploi.io/projects/6-api-level-requests/items/64-install-new-php-version-on-server