python/visu [DOC]: refer to foutra in comments in specplot.py

src/python/visu/specplot.py

@@ -10,6 +10,9 @@
 # 
 # Purpose: Plot the power spectrum.
 #
+# This program is primarily provided to plot data from two-column files
+# as produced by foutra.
+#
 # ----
 #
 # This program is free software: you can redistribute it and/or modify
@@ -91,6 +94,10 @@ def help():
   help_text = \
   """
 -------------------------------------------------------------------------------
+
+This program is primarily provided to plot data from two-column files
+as produced by foutra.
+
  -v|--verbose         Be verbose.
  -h|--help            Display this help.
  --overwrite          Overwrite output file if existing.