chore: update readme

Signed-off-by: Florent BENOIT <[email protected]>

Author: benoitf

README.md

@@ -7,3 +7,8 @@ running on top of the container engine.
 
 You can initialize a MicroShift cluster using the Resources section in Settings
 once the `minc` binary is installed on your machine.
+
+
+# development version
+
+Install the custom extension `ghcr.io/minc-org/minc-extension:next` to try the extension published after each commit.