CLOUDP-293595: add flex cluster example to the atlas cluster create command (#3526)

Author: andreaangiolillo

docs/command/atlas-clusters-create.txt

@@ -187,6 +187,13 @@ Examples
    atlas cluster create myCluster --projectId 5e2211c17a3e5a48f5497de3 --provider AWS --region US_EAST_1 --tier M0
 
 
+.. code-block::
+   :copyable: false
+
+   # Deploy a Flex cluster named myFlexCluster for the project with the ID 5e2211c17a3e5a48f5497de3 and tag "env=dev":
+   atlas cluster create myFlexCluster --projectId 5e2211c17a3e5a48f5497de3 --provider AWS --region US_EAST_1 --tier FLEX --tag env=dev
+
+   
 .. code-block::
    :copyable: false
 

internal/cli/clusters/create.go

@@ -362,6 +362,9 @@ For full control of your deployment, or to create multi-cloud clusters, provide
 		Example: `  # Deploy a free cluster named myCluster for the project with the ID 5e2211c17a3e5a48f5497de3:
   atlas cluster create myCluster --projectId 5e2211c17a3e5a48f5497de3 --provider AWS --region US_EAST_1 --tier M0
 
+  # Deploy a Flex cluster named myFlexCluster for the project with the ID 5e2211c17a3e5a48f5497de3 and tag "env=dev":
+  atlas cluster create myFlexCluster --projectId 5e2211c17a3e5a48f5497de3 --provider AWS --region US_EAST_1 --tier FLEX --tag env=dev
+
   # Deploy a free cluster named myCluster for the project with the ID 5e2211c17a3e5a48f5497de3 and tag "env=dev":
   atlas cluster create myCluster --projectId 5e2211c17a3e5a48f5497de3 --provider AWS --region US_EAST_1 --tier M0 --tag env=dev