Fix extra spaces appended to example lines (vaadin#3774)

Author: MatthewVaadin

articles/control-center/getting-started/index.adoc

@@ -21,14 +21,33 @@ Also, you'll need to install https://helm.sh/[Helm]. It's a Kubernetes package m
 
 To deploy Control Center to your Kubernetes cluster, run the following Helm command:
 
+++++
+<style>
+.linenums code[class*='language-'] > span {
+  counter-increment: line-number;
+}
+.linenums code[class*='language-'] > span::before {
+  content: counter(line-number);
+  color: var(--docs-code-comment-color);
+  font-size: var(--docs-font-size-xs);
+  display: inline-block;
+  min-width: 1em;
+  padding-inline-end: 0.5em;
+  margin-inline-end: 1em;
+  text-align: end;
+  border-right: 1px solid var(--docs-code-comment-color);
+}
+</style>
+++++
+
 .Terminal
-[source,bash]
+[.linenums,source,bash]
 ----
-helm install control-center oci://docker.io/vaadin/control-center \  # (1)
-    -n control-center --create-namespace \  # (2)
-    --set serviceAccount.clusterAdmin=true \  # (3)
-    --set service.type=LoadBalancer --set service.port=8000 \  # (4)
-    --wait  # (5)
+helm install control-center oci://docker.io/vaadin/control-center \
+    -n control-center --create-namespace \
+    --set serviceAccount.clusterAdmin=true \
+    --set service.type=LoadBalancer --set service.port=8000 \
+    --wait
 ----
 
 <1> This installs Control Center.