Add info on usage

colour.tex

@@ -67,4 +67,12 @@
 \ct{0.37}{0.53}{0.00}{Herbin Vert Empire}&        64 &\cr
 }
 
+\vfill
+
+{\leftskip=15mm \rightskip=15mm \noindent To access these colours in XTerm, send {\tt ESC [ 3 8 ; 5 ;}{\it n}{\tt\ m},
+where {it n} is the number from the coloured box. To set the background
+colour, use 48 instead of 38.\par}
+
+
+
 \bye