compute_instance_template: Remove copy/paste typo in docs (#3241)

The allow_stopping_for_update argument is
not defined for compute_instance_template,
so remove this typo in the docs. That field
is defined for compute_instance, so I think
it is a copy/paste typo.

website/docs/r/compute_instance_template.html.markdown

@@ -190,8 +190,6 @@ The following arguments are supported:
 
 * `machine_type` - (Required) The machine type to create.
 
-    **Note:** If you want to update this value (resize the VM) after initial creation, you must set [`allow_stopping_for_update`](#allow_stopping_for_update) to `true`.
-
     To create a machine with a [custom type][custom-vm-types] (such as extended memory), format the value like `custom-VCPUS-MEM_IN_MB` like `custom-6-20480` for 6 vCPU and 20GB of RAM.
 
 - - -