message: Improve description for tf.test.is_gpu_available
diff: @@ -1331,13 +1331,16 @@ def run_cuda_only(func=None):
  def is_gpu_available(cuda_only=False, min_cuda_compute_capability=None):
  """Returns whether TensorFlow can access a GPU.
  + Warning: if not GPU version of the package is installed, the function would
  + also, return False.
  +
  Args:
  - cuda_only: limit the search to CUDA gpus.
  + cuda_only: limit the search to CUDA GPUs.
  min_cuda_compute_capability: a (major,minor) pair that indicates the minimum
  CUDA compute capability required, or None if no requirement.
  Returns:
  - True if a gpu device of the requested kind is available.
  + True if a GPU device of the requested kind is available.
  """
  def compute_capability_from_device_desc(device_desc):
  