add etldoc to layer_highway ( v2 )

gen_etl_graph_highway.sh

@@ -0,0 +1,21 @@
+
+
+DOT=highway.dot
+
+echo "digraph G
+{    
+rankdir=LR;
+" > $DOT
+
+cat ./layers/highway/mapping.yaml        | grep    "# etldoc:" |  sed 's/# etldoc://g'  >>$DOT
+cat ./layers/highway/types.sql           | grep "\-\- etldoc:" |  sed 's/-- etldoc://g' >>$DOT
+cat ./layers/highway/ne_global_roads.sql | grep "\-\- etldoc:" |  sed 's/-- etldoc://g' >>$DOT 
+cat ./layers/highway/highway.sql         | grep "\-\- etldoc:" |  sed 's/-- etldoc://g' >>$DOT
+
+echo "
+}
+" >> $DOT
+
+cat $DOT
+
+dot -Tpng $DOT > layer_highway_etl.png