[chore] update README (#1598)

Author: atoulme

functional_tests/README.md

@@ -6,15 +6,15 @@ Run the following commands prior to running the test locally:
 ```
 export KUBECONFIG=/tmp/kube-config-splunk-otel-collector-chart-functional-testing
 export KUBE_TEST_ENV=kind
-export K8S_VERSION=v1.28.0
+export K8S_VERSION=v1.29.0
 kind create cluster --kubeconfig=/tmp/kube-config-splunk-otel-collector-chart-functional-testing --config=.github/workflows/configs/kind-config.yaml --image=kindest/node:$K8S_VERSION
 kubectl get csr -o=jsonpath='{range.items[?(@.spec.signerName=="kubernetes.io/kubelet-serving")]}{.metadata.name}{" "}{end}' | xargs kubectl certificate approve
 make cert-manager
 kind load docker-image quay.io/splunko11ytest/nodejs_test:latest --name kind
 kind load docker-image quay.io/splunko11ytest/java_test:latest --name kind
 kind load docker-image quay.io/splunko11ytest/dotnet_test:latest --name kind
 # On Mac M1s, you can also push this image so kind doesn't get confused with the platform to use:
-kind load docker-image ghcr.io/signalfx/splunk-otel-dotnet/splunk-otel-dotnet:v1.6.0 --name kind
+kind load docker-image ghcr.io/signalfx/splunk-otel-dotnet/splunk-otel-dotnet:v1.8.0 --name kind
 kind load docker-image ghcr.io/signalfx/splunk-otel-js/splunk-otel-js:v2.4.4 --name kind
 kind load docker-image ghcr.io/signalfx/splunk-otel-java/splunk-otel-java:v1.30.0 --name kind
 ```