website
, copyright
, licensing
I’m starting a knowledge base where I want content (text and images) to be freely submitted and edited without requiring registration from my users, so they collectively can build an index in this particular subject.
I’ve searched far and wide but I just don’t understand what I should be looking for.
Take a look at what Wikipedia did for handling this exact issue in terms of licensing the content as well as specifically contributor's rights and obligations. Wikipedia requires users who submit content to confirm their compliance with these policies for any edits to their pages before accepting their changes: it's hard-wired into the edit-preview-submit workflow.
On a separate note, you can also use the software behind Wikipedia if you like their work flow; it's called MediaWiki and it's open source (not to be confused with WikiMedia Foundation, the organization behind Wikipedia and MediaWiki).
All content is licensed under CC BY-SA 3.0.