If it's a change that affects the requirements, then yes, the document needs to be updated and versioned. But there are changes that don't affect the requirements. In that case, it might mean that the document has a hole and it should be added. Or it might mean that the change really doesn't affect the requirements and the document is fine.
Some change requests turn out to be data issues -- they don't affect the document. Some are minor tweaks that aren't documented anyway (perhaps the drop list doesn't fit when the screen resolution is set in some way, and the document never got anywhere near detailed to talk about screen resolutions or did more than mention that that field has a drop list filled by some source).
Read the document. If the change makes anything in the document incorrect, then update the spec. If the change is something that you wish you'd known about, something that would be useful to people in the future, then add it to the spec.