client side validation can't have docs with explicit choices (#258)

Signed-off-by: Modular Magician <magic-modules@google.com>

plugins/modules/gcp_compute_image.py

@@ -91,9 +91,8 @@ options:
           For newer Windows images, the server might also populate this property with
           the value WINDOWS to indicate that this is a Windows image. This value is
           purely informational and does not enable or disable any features.
+        - 'Some valid choices include: "VIRTIO_SCSI_MULTIQUEUE"'
         required: false
-        choices:
-        - VIRTIO_SCSI_MULTIQUEUE
   image_encryption_key:
     description:
     - Encrypts the image using a customer-supplied encryption key.
@@ -134,9 +133,8 @@ options:
         - The format used to encode and transmit the block device, which should be
           TAR. This is just a container and transmission format and not a runtime
           format. Provided by the client when the disk image is created.
+        - 'Some valid choices include: "TAR"'
         required: false
-        choices:
-        - TAR
       sha1_checksum:
         description:
         - An optional SHA1 checksum of the disk image before unpackaging.
@@ -179,9 +177,8 @@ options:
     description:
     - The type of the image used to create this disk. The default and only value is
       RAW .
+    - 'Some valid choices include: "RAW"'
     required: false
-    choices:
-    - RAW
 extends_documentation_fragment: gcp
 notes:
 - 'API Reference: U(https://cloud.google.com/compute/docs/reference/v1/images)'