We are quite small and lacking in documentation but I encourage the team to add pages about functionality and anything special/useful:
How to set up test data for a specific test
Flow diagram/decision diagrams which show the different scenarios
Mind Maps of what is being tested (we have one big master mind map and take branches as appropriate and expand these and copy them back in)
Tutorials on certain tools
Is this the sort of thing you were looking for?
We are not audited in the test department so do not have to follow certain templates like many financial institutions.