https://www.blender.org/manual/modeling/curves/selecting.html
It says:
"Every Nth
Mode: Edit mode
Menu: Select ‣ Every Nth
................"
That button doesnt exist. But something similar does.
Its called "checker deselect"
But its already mentioned earlier in the manual and you already linked back to it.
So im guessing just deleting the part on the non-existing button would
work.
Unless im missing something.