actually show first graph and tell users how to edit

tsa/howto/new-machine.mdwn

@@ -162,10 +162,9 @@ All commands to be run as root unless otherwise noted.
 ## Design
 
 If you want to understand better the different installation procedures there is a
-install flowchart:
+install flowchart that was made on [Draw.io](https://draw.io). 
 
-* [PNG](./install.png)
-* [drawio](./install.drawio)
+[[install.png]]
 
 There are also per-site install graphs:
 
@@ -173,6 +172,10 @@ There are also per-site install graphs:
  * [install-hetzner-robot.png](install-hetzner-robot.png)
  * [install-ganeti.png](install-ganeti.png)
 
+To edit those graphics, head to the <https://draw.io> website (or
+install their Electron desktop app) and load the [install.drawio](./install.drawio)
+file.
+
 Those diagrams were created as part of the redesign of the install
 process, to better understand the various steps of the process and see
 how they could be refactored. They should not be considered an