🔨 chore: add KUBECONFIG check (and reword it)

Signed-off-by: dyn <oss+dyn@xtrm.me>

p3/scripts/argo-install.sh

@@ -1,5 +1,13 @@
 #!/usr/bin/env sh
 
+if [ -z "$KUBECONFIG" ]; then
+  echo "KUBECONFIG is not set!"
+  echo
+  echo "You can add it to your .bashrc or .zshrc:"
+  echo '> export KUBECONFIG="$HOME/.kube/config"'
+  exit 1
+fi
+
 k3d cluster create inception-of-things
 
 # Setup a metrics-server to prevent dumb errors