Update pager.md
Update pager.md

Added max_pages configuration documentation.
martiis/FilterManagerBundle,asev/FilterManagerBundle,mansimas/FilterManagerBundle,ongr-io/FilterManagerBundle,mansimas/FilterManagerBundle,martiis/FilterManagerBundle,Dariusp/FilterManagerBundle,murnieza/FilterManagerBundle,saimaz/FilterManagerBundle,Dariusp/FilterManagerBundle,murnieza/FilterManagerBundle,saimaz/FilterManagerBundle,asev/FilterManagerBundle