Update installing-stack-demo-self.asciidoc to mitigate error-handling issue. update variable on tail command (#3015)

* Update installing-stack-demo-self.asciidoc

Adding an Important clarification. The enrollment script fails without proper error handling if the second node is not able to access the first node. the elasticsearch.yml ends up modified and the enrollment script is unable to be reran without undoing all the changes. Reminder added to ensure network access is available before proceeding.

second. the tail command is incorrect unless the cluster.name is also elasticsearch-demo. this value defaults to cluster.name

* nit to trigger CI

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Co-authored-by: Liam Thompson <32779855+leemthompo@users.noreply.github.com>

Author: rich-cabrera

docs/en/install-upgrade/installing-stack-demo-self.asciidoc

@@ -305,6 +305,12 @@ Note the following tips about enrollment tokens:
 ====
 
 . In the terminal shell for your second {es} node, pass the enrollment token as a parameter to the `elasticsearch-reconfigure-node` tool:
+[IMPORTANT]
+====
+Be sure the second node is able to access the first node before running the following command. You can test this by running a curl command to the first node at port 9200.
+
+If you are unable to access the first node, modify your network configuration before proceeding.
+====
 +
 [source,"shell"]
 ----
@@ -352,11 +358,11 @@ network.host: 10.128.0.132
 sudo systemctl start elasticsearch.service
 ----
 
-. **Optionally**, to view the progress as the second {es} node starts up and connects to the first {es} node, open a new terminal into the second node and `tail` the {es} log file:
+. **Optionally**, to view the progress as the second {es} node starts up and connects to the first {es} node, open a new terminal into the second node and `tail` the {es} log file. Be sure to replace <CLUSTER.NAME> with the cluster.name you set earlier in the first node's elasticsearch.yml:
 +
 [source,"shell"]
 ----
-sudo tail -f /var/log/elasticsearch/elasticsearch-demo.log
+sudo tail -f /var/log/elasticsearch/<CLUSTER.NAME>.log
 ----
 +
 Notice in the log file some helpful diagnostics, such as: