Required minimum Node.js bump for Azure SDK

Minimum Node.js version may be incorrect

This issue was created because the following file has been flagged with an out-of-date version number for Node.js: Tutorials/Bing-Image-Search/README.md

Required Fix: The Azure SDK now supports a minimum Node.js version of LTS (long term support).

Please fix this file to indicate LTS support and remove the specific version number it currently references found on line 16. If you find your code sample no longer works when moving up to the LTS version, please log an issue against the specific Azure SDK at https://github.com/azure/azure-sdk-for-js.

Required Exception If you can't change this file to support the minimum LTS of Node.js, please comment on this issue with the reason and details so we can refine our file search.

#DocIndexProject_nodejs

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#### Document Details

* Content: []()
* Content Source: [Tutorials/Bing-Image-Search/README.md](https://github.com/Azure-Samples/cognitive-services-REST-api-samples/tree/master/Tutorials/Bing-Image-Search/README.md)
* Service: ****
* GitHub Login: @
* Microsoft Alias: ****