fix make command for generating manifests

make generate does not generate the CRDs in config/crd/base the correct command to accomplish this is make manifests. See Makefile:

generate: controller-gen  ## Generate code (deepcopy)
	$(CONTROLLER_GEN) object:headerFile="hack/boilerplate.go.txt" paths="./..."

manifests: controller-gen  ## Generate manifests (CRDs, RBAC, etc.)
	$(CONTROLLER_GEN) rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases

docs/book/src/getting-started.md

@@ -125,7 +125,7 @@ Now, see our example fully completed.
 
 #### Generating manifests with the specs and validations
 
-To generate the required CRDs we will run `make generate` command, which will call [controller-gen][controller-gen]
+To generate the required CRDs we will run `make manifests` command, which will call [controller-gen][controller-gen]
 to generate the CRD manifest, which is located under the `config/crd/bases` directory.
 
 <details><summary><code>config/crd/bases/cache.example.com_memcacheds.yam</code>: Our Memcached CRD</summary>