category_graph: update help

Change-Id: I405deea82438b8b1c0f401156d9156580b4cd6fa
---
M scripts/category_graph.py
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/scripts/category_graph.py b/scripts/category_graph.py
index 33ec5f7..cd810a3 100755
--- a/scripts/category_graph.py
+++ b/scripts/category_graph.py
@@ -13,14 +13,15 @@
 
 optional arguments:
   -to TO         base file name to save, "?" to ask.
-  -style STYLE   graphviz style definitions in dot format.
+  -style STYLE   graphviz style definitions in dot format:
+                 https://graphviz.org/doc/info/attrs.html
   -depth DEPTH   maximal hierarchy depth. 2 by default.
   -downsize K    font size divider for subcategories. 4 by default.
                  Use 1 for the same font size.
 
 Examples:
 
-pwb.py -v graph category
+pwb.py -v category_graph -from
 pwb.py category_graph -from Life -downsize 1.5 \
         -style 'graph[rankdir=BT ranksep=0.5] node[shape=circle
         style=filled fillcolor=green] edge[style=dashed penwidth=3]'

