This is an example set up, how the wiki could work and also how external user could make contributions.
TOC page, categories to create hierarchy
For Editors:Lost your password?
Also,I have used redirection for the /wiki > /welcome-to ( since the headpage (i.e. /wiki is not editable) to work around wiki-landing pages and menu localization.
users will need a login account. With this account they will only have access to edit wikipages(WikiAuthor)