Merge pull request #64882 from AedinC/OCPBUGS-16665

[OCPBUGS-16665]: Added info about --machine-cidr flag to Create HCP clus…

Author: mburke5678

modules/rosa-hcp-sts-creating-a-cluster-cli.adoc

@@ -34,14 +34,19 @@ To successfully install ROSA clusters, use the latest version of the ROSA CLI (`
 //REGION="<region>"
 //----
 
-. You can create your {hcp-title} cluster with one of the following commands. 
-
+. You can create your {hcp-title} cluster with one of the following commands.
++
+[NOTE]
+====
+When creating a {hcp-title} cluster, the default machine Classless Inter-Domain Routing (CIDR) is `10.0.0.0/16`. If this does not correspond to the CIDR range for your VPC subnets, add `--machine-cidr <address_block>` to the following commands. To learn more about the default CIDR ranges for {product-title}, see xref:../networking/cidr-range-definitions.adoc[CIDR range definitions].
+====
++
 ** Create a cluster with a single, initial machine pool, publicly available API, and publicly available Ingress by running the following command:
 +
 [source,terminal]
 ----
 $ rosa create cluster --cluster-name=<cluster_name> \
-    --sts --mode=auto --hosted-cp --operator-roles-prefix <operator-role-prefix> \ 
+    --sts --mode=auto --hosted-cp --operator-roles-prefix <operator-role-prefix> \
     --oidc-config-id <ID-of-OIDC-configuration> --subnet-ids=<public-subnet-id>,<private-subnet-id>
 ----
 
@@ -85,4 +90,4 @@ If the installation fails or the `State` field does not change to `ready` after
 ----
 $ rosa logs install --cluster=<cluster_name> --watch <1>
 ----
-<1> Optional: To watch for new log messages as the installation progresses, use the `--watch` argument.
+<1> Optional: To watch for new log messages as the installation progresses, use the `--watch` argument.