adding readme file for testing and cli generation (#7809)

specification/imagebuilder/resource-manager/readme.cli.md

@@ -0,0 +1,21 @@
+## CLI
+
+These settings apply only when `--cli` is specified on the command line.
+
+``` yaml $(cli)
+cli:
+  namespace: azure.mgmt.imagebuilder
+  flatten-all: true
+  test-scenario:
+    - name: Create an Image Template.
+    - name: Create an Image Template with a user assigned identity configured
+    - name: Retrieve single runOutput
+    - name: Retrieve a list of all outputs created by the last run of an Image Template
+    - name: Retrieve an Image Template.
+    - name: List images by resource group
+    - name: List images by subscription.
+    - name: Create image(s) from existing imageTemplate.
+    - name: Remove identities for an Image Template.
+    - name: Update the tags for an Image Template.
+    - name: Delete an Image Template.
+```