Quentin 04/10/2019: add more info on ECRAD external data link usage

A-INSTALL

@@ -1076,9 +1076,13 @@ etc ...
 # REM : the 'profile_mesonh...' file & the 'dir_obj...' directory will be suffixed with an ECRAD extension 
 #
 #  Usage :
-#   1) In namelist replace RAD='ECMW' be RAD='ECRA' 
-#   2) Add link to 'ecrad-1.0.1/data' files 
-#      see 007_16janvier/008_run2 test case for example
+#   1) In namelist replace RAD='ECMW' by RAD='ECRA' 
+#   2) Add link to all 'ecrad-1.0.1/data' files in your mesonh run directory
+ln -sf ${SRC_MESONH}/src/LIB/RAD/ecrad-1.0.1/data/* .
+#
+# REM : you can replace CDATADIR = "." by CDATADIR = "data" of ini_radiations_ecrad.f90 to link only the data folder instead of all the files one by one
+#
+# See 007_16janvier/008_run2 test case for example
 #
 # d) MNH_MEGAN for optional compilation of MEGAN code 
 # --------------------------------------