r.topmodel reference: Korea => South Korea (#1534)

raster/r.topmodel/r.topmodel.html

@@ -146,7 +146,7 @@ boundary. The entire range of topographic index values will be divided into
 
   <li>Cho, H., 2000. GIS Hydrological Modeling System by Using Programming
   Interface of GRASS. Master's Thesis, Department of Civil Engineering,
-  Kyungpook National University, Korea.
+  Kyungpook National University, South Korea.
 
   <li>Liaw, S. C., 1988. Streamflow Simulation Using a Physically Based
   Hydrologic Model in Humid Forested Watersheds. Dissertation, Colorado State