I have used Moodle for a long time. It installs easily (even with a *AMP stack)

https://www.zend.com/blog/choosing-right-php-stack

Or your own Apache, php, *sql.

I installed it on my laptop to document work, and on small company servers to share documentation, with the additional ability to add discussions and so on.

Mainly, getting started was easy, and the available formats were easy for people to grasp.