Docu update

doc/tex/intro.tex

-{\CDI} is an Interface to access Climate and NWP model Data.
+{\CDI} is an Interface to access Climate and forecast model Data.
 The interface is independent from a specific data format and has a C and Fortran API.
 {\CDI} was developed for a fast and machine independent access to GRIB
 and netCDF datasets with the same interface.