Fix typo in demo update instructions for k8ssandra (pixie-io#1719)

Summary: TSIA

Type of change: /kind cleanup

Test Plan: N/A

Signed-off-by: Benjamin Kilimnik <bkilimnik@pixielabs.ai>

demos/README.md

@@ -82,7 +82,7 @@ file describes the demo scenarios.
     kustomize build . > k8ssandra-control-plane.yaml
     ```
 
-5. Concatenate the yaml files in the order specified below and copy it into `pixie/demos/kafka`.
+5. Concatenate the yaml files in the order specified below and copy it into `pixie/demos/k8ssandra`.
 
     ```shell
     cat crd.yaml k8ssandra-control-plane.yaml petclinic.yaml > demos/k8ssandra/k8ssandra.yaml