Remove or update zh-cn translation from installation instructions
The latest version of Tensorflow does not support GPU on Windows Native. However, the [zh-cn translation](https://www.tensorflow.org/install/pip?hl=zh-cn) says nothing about it. The translation has now been outdated and misleading.

When I tried to contribute to the [l10n](/tensorflow/docs-l10n/), I only found a "[DO_NOT_TRANSLATE](/tensorflow/docs-l10n/blob/master/site/zh-cn/install/DO_NOT_TRANSLATE)" file, and the [README](/tensorflow/docs-l10n#do-not-translate) says, "tensorflow.org does not translate time-sensitive sections like the installation instructions."

If the installation instructions will not be translated any more, please remove the translation.