[handbook] Updated dune-subgrid description in 2_detailedinstall.tex

doc/handbook/2_detailedinstall.tex

@@ -285,7 +285,8 @@ and some more libraries and tools which are prerequisites for their use.
 \item \textbf{opm-grid}: opm-grid is a DUNE module supporting grids in a corner-point format.
   Download: \url{https://github.com/OPM/opm-grid.git}
   
-\item \textbf{dune-subgrid}: The dune-subgrid module allows to mark elements of another hierarchical dune grid.
+\item \textbf{dune-subgrid}: The dune-subgrid module is a meta-grid implementation that allows 
+to mark elements of another hierarchical dune grid and use this sub-grid just like a regular grid.
 The set of marked elements can then be accessed as a hierarchical dune grid in its own right.
 Dune-Subgrid provides the full grid interface including adaptive mesh refinement.
   Download: \url{https://git.imp.fu-berlin.de/agnumpde/dune-subgrid.git}