* Adding supported language codes from Google Translate
Added all languages that Google Translate supports.
* Corrected alphabetical order of languages
* Remove languages not actually supported for speech
Previously I added languages supported by Google Translate. Based on comments received, I manually verified each language, and removed languages that are not actually supported for speech in Google Translate.
* Add instructions to update the list of supported languages
Added instructions as suggested so as to facilitate easier update on this list.
* Reformat comment in const.py
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Co-authored-by: Erik Montnemery <erik@montnemery.com>