message: Add useful message to unchanging file
diff: #
  # Update this file with your device and supported types
  # - please don't check it in!
  +# - if you want to remove it from 'git status' then you can do:
  +# git update-index --assume-unchanged tensorflow/compiler/tests/plugin.bzl
  #
  -plugin_device = ""
  +plugin_device = "XLA_IPU"
  plugin_types = "DT_FLOAT,DT_INT32"
  +
  