fix typo in oecosimu.Rd (reported by Jimmy O'Donnell, UCSC)

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2638 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
spec/renyi/tsallis accum gained 'subset'

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2641 edb9625f-4e0d-4859-8d74-9fd3b1da38cb