Tighten up doc of l3keys.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4514 de43f980-851b-0410-b2f7-c40aca1f87e0
Those two functions should be :Nn, not :NN.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4515 de43f980-851b-0410-b2f7-c40aca1f87e0