Legacy service accounts: Update log6x-collection-setup.adoc

- More than one command is mentioned in the single code block
- Here is the documentation link  [1]:
 [1] https://docs.openshift.com/container-platform/4.18/observability/logging/logging-6.0/log6x-clf.html#legacy-service-accounts
- As per the standard rule, using more than one command per code block is not recommended.
- Please check Standard rule  [2] for reference:
 [2] https://github.com/openshift/openshift-docs/blob/main/contributing_to_docs/doc_guidelines.adoc#single-command-per-code-block
- When commands are bunched together, the copy to clipboard functionality might not break the lines up correctly. Using a single command per code block makes it copy-and-paste friendly.
- Hence we need to mention 2 separate code blocks for above 2 commands.
- Here is the updated look of the documentation:
~~~
$ oc adm policy add-cluster-role-to-user collect-application-logs system:serviceaccount:openshift-logging:logcollector 
~~~

~~~
$ oc adm policy add-cluster-role-to-user collect-infrastructure-logs system:serviceaccount:openshift-logging:logcollector
~~~

Author: prithvipatil97

modules/log6x-collection-setup.adoc

@@ -18,6 +18,10 @@ To use the existing legacy service account `logcollector`, create the following
 [source,terminal]
 ----
 $ oc adm policy add-cluster-role-to-user collect-application-logs system:serviceaccount:openshift-logging:logcollector
+----
+
+[source,terminal]
+----
 $ oc adm policy add-cluster-role-to-user collect-infrastructure-logs system:serviceaccount:openshift-logging:logcollector
 ----