Ask HN: What is a good system for program specs?

I am looking for a system that I can use to manage and collaboratively edit programming specifications and requirement docs. 1. web based 2. open source 3. Have basic access control 4. Show history / changes of a document 5. Be easy to use for non-technical people ( not command line git) 6. export to popular formats such as docx and pdf 7. have a basic search feature where I could look by keyword of changed docs by a date range or all doc versions as of a specific date.