Adds description for default value of cpuidle field (GoogleCloudPla…

…tform#10005)

* add description

* remove tail space

mmv1/products/cloudrunv2/Service.yaml

@@ -430,7 +430,8 @@ properties:
                 - !ruby/object:Api::Type::Boolean
                   name: 'cpuIdle'
                   description: |-
-                    Determines whether CPU should be throttled or not outside of requests.
+                    Determines whether CPU is only allocated during requests. True by default if the parent `resources` field is not set. However, if
+                    `resources` is set, this field must be explicitly set to true to preserve the default behavior.
                 - !ruby/object:Api::Type::Boolean
                   name: 'startupCpuBoost'
                   description: |-