General availability: Custom Translator – May new features, improvements and bug fixes

In May 2021, the following updates and enhancement were made to Custom Translator: * New training pipeline to improve the custom model generalisation and capacity to retain more customer terminology (words and phrases). * Refreshed Custom Translator baselines to fix word alignment bug. View the list of affected language pairs [here](https://docs.microsoft.com/azure/cognitive-services/translator/custom-translator/release-notes). * Translator * Services