Phriction should be able to let users leave comments to any wiki page they can read. This feature are useful for these two scenarios:
# A wiki page is readonly to me, but i'd like to give some suggestions or share some thoughts related to the content.
# I have edit access to the wiki page, but I just want to call out some special thing, don't want to change the original content.
Similar to T1894 but these comments don't need to be inline.