belfast-1: updated tutorial to make it work with plumed23

user-doc/tutorials/belfast-1.txt

@@ -261,14 +261,16 @@ PRINT ARG=abeta.lessthan,dd.mean,dd.min,dd.max,dd.moment-2 STRIDE=1 FILE=COLVAR
 
 HISTOGRAM ...
 ARG=abeta.lessthan,dd.mean
+LABEL=hh
 USE_ALL_DATA
 KERNEL=discrete
 GRID_MIN=0,0.8
 GRID_MAX=4,1.2
 GRID_BIN=40,40
-GRID_WFILE=histo
 ... HISTOGRAM
 
+DUMPGRID GRID=hh FILE=histo
+
 ENDPLUMED
 \endverbatim
 
@@ -286,15 +288,17 @@ and the BANDWIDTH should be smaller (i.e. one order of magnitude) than the varia
 
 \verbatim
 HISTOGRAM ...
+LABEL=hh
 ARG=abeta.lessthan,dd.mean
 USE_ALL_DATA
 GRID_MIN=0,0.8
 GRID_MAX=4,1.2
 GRID_SPACING=0.04,0.004
 BANDWIDTH=0.08,0.008
-GRID_WFILE=histo
 ... HISTOGRAM
 
+DUMPGRID GRID=hh FILE=histo
+
 ENDPLUMED
 \endverbatim