doc: update the Artifacts with the latest changes on the EnvTest Make…

…file target configurations

docs/book/src/reference/artifacts.md

@@ -45,9 +45,26 @@ The artefacts for [ENVTEST][env-test-doc] k8s `1.31` are exclusively available a
 You can refer to the Makefile of the Kubebuilder scaffold and observe that the envtest setup is consistently aligned across all controller-runtime releases. Starting from `release-0.19`, it is configured to automatically download the artefact from the correct location, **ensuring that kubebuilder users are not impacted.**
 
 ```shell
-ENVTEST_K8S_VERSION = 1.31.0
-ENVTEST_VERSION ?= release-0.19
+## Tool Binaries
+..
+ENVTEST ?= $(LOCALBIN)/setup-envtest
 ...
+
+## Tool Versions
+...
+#ENVTEST_VERSION is the version of controller-runtime release branch to fetch the envtest setup script (i.e. release-0.20)
+ENVTEST_VERSION ?= $(shell go list -m -f "{{ .Version }}" sigs.k8s.io/controller-runtime | awk -F'[v.]' '{printf "release-%d.%d", $$2, $$3}')
+#ENVTEST_K8S_VERSION is the version of Kubernetes to use for setting up ENVTEST binaries (i.e. 1.31)
+ENVTEST_K8S_VERSION ?= $(shell go list -m -f "{{ .Version }}" k8s.io/api | awk -F'[v.]' '{printf "1.%d", $$3}')
+...
+.PHONY: setup-envtest
+setup-envtest: envtest ## Download the binaries required for ENVTEST in the local bin directory.
+	@echo "Setting up envtest binaries for Kubernetes version $(ENVTEST_K8S_VERSION)..."
+	@$(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path || { \
+		echo "Error: Failed to set up envtest binaries for version $(ENVTEST_K8S_VERSION)."; \
+		exit 1; \
+	}
+
 .PHONY: envtest
 envtest: $(ENVTEST) ## Download setup-envtest locally if necessary.
 $(ENVTEST): $(LOCALBIN)