Merge pull request #11880 from k8s-infra-cherrypick-robot/cherry-pick-11875-to-release-1.9

[release-1.9] 📖 Update Vultr quick-start docs

Author: k8s-ci-robot

docs/book/src/user/quick-start.md

@@ -821,10 +821,10 @@ project][vSphere getting started guide].
 {{#tab Vultr}}
 
 ```bash
-export VULTR_API_KEY=<your_api_key>
+export VULTR_API_KEY="$(echo -n "${VULTR_API_KEY}" | base64 | tr -d '\n')"
 
 # initialize the management cluster
-clusterctl init --infrastructure vultr
+clusterctl init --infrastructure vultr-vultr
 ```
 {{#/tab }}
 {{#/tabs }}