Usage doc: Clarify commands groups (#472)

README.md

@@ -50,6 +50,17 @@ There is two kind of images. One build with `pip` for user purposes, and one usi
 silkaj <sub-command>
 ```
 
+Silkaj command line interface (CLI) is structured by groups of commands:
+
+```sh
+silkaj blockchain -h
+silkaj money -h
+silkaj money transfer -h
+silkaj wot revocation -h
+```
+
+You can find commands at the root, such as `silkaj license`
+
 - Will automatically request and post data on https://g1.duniter.org/node/summary official Ğ1 endpoint based on a load balancer.
 
 - Specify a custom node with `-ep` option where `<port>` and `<path>` are optional: