We have already pointed out elsewhere that in agile requirements engineering less has to be written and more can also be communicated verbally, but: Some documentation should (or sometimes must) still be created. In order to avoid that this documentation ends up in uncontrolled growth, we suggest to make one person in the team responsible for it. We call this role the documentation gardener. Of course, the overall responsibility for good requirements lies with the product owner. However, a gardener can often relieve the PO w.r.t.documentation.
A gardener has (at least) two tasks: planting new things and trimming or maintaining existing ones. In terms of (requirements) documentation, your docu-gardener should ensure the appropriate form and content, while actively searching for and removing parts that are no longer needed.
We explain how docu-gardeners can perform their role in Tip B-7.