https://pmwiki.org/ (https://pmwiki.org/)
Pmwiki is a lighter version clone of MediaWiki. It still uses the standard Wiki Markup Language that most all use to format your pages. Wikis are a little complicated and take some practice to get use to, but the average computer user can pick up by clicking Edit an the page of any Wiki to see examples of how it was used.
Big Kahuna Hosting can install the if you prefer someone with experience doing it.
http://www.bigkahunahosting.com/hosting-services/ (http://www.bigkahunahosting.com/hosting-services/)