docs: Add kube config backup documentation

README.md

@@ -12,6 +12,14 @@
 apt install make git vagrant ansible
 ```
 
+## Before starting
+If you have already configured kubernetes clusters on your machines (`~/.kube/config` exists and not empty), backup your keys as follows:
+```
+cp ~/.kube/config ~/.kube/config-base
+```
+
+This way, your already configured keys will be onboarded with the current pipeline, and ported to the resulting configuration file.
+
 ## Setup
 Clone the whole repository, including submodules
 ```