Update README.md

[Louis-7]

Correct locale parameter. Change "en-US" to "en_US" since "en-US" totally not working.

[ohtangza]

@Louis-7 Can you clarify your device condition? According to Apple's docs regarding locales (https://developer.apple.com/library/content/documentation/MacOSX/Conceptual/BPInternational/LanguageandLocaleIDs/LanguageandLocaleIDs.html), it seems that en-US seems to be right. It's also ISO standard string.

I'm also in use of this library and had no chance to encounter malfunctioning with this string.

[Louis-7]

Hi, sorry for late response. I'm using android.

I was raise an issue here #86

@jamsch, Could you answer the question from ohtangza?

[jamsch]

I looked at the link you sent @ohtangza Specifically this portion says to use the format:
[language designator]_[region designator] which follows the en_US pattern.

Here's a list of locale IDs for iOS
https://gist.github.com/xta/6e9b63db1fa662bb3910b680f9ebd458

For Android, I don't think it matters so much but it seems like most examples use Language tags which returns [lang]-[region] however Locale.toString() returns [lang]_[region] and LocaleList.getDefault() returns the same format.

RecognizerIntent/EXTRA_LANGUAGE_PREFERENCE says to "use a locale string like 'en-US'." and doesn't elaborate beyond that.

[Louis-7]

I did some search and I find a post here -> How to set the language in speech recognition on android? which excetly match the source code, it says "en-US" is the right parameter.

But on my phone I'm sure about that [language designator]-[region designator] is not working for me, maybe I'm using a different language option from "en-US" but when you guys test the library you just use the English by default?

Maybe different version of OS have different format of language options. We may do more test on it.

[jamsch]

@Louis-7
Yeah, I also read that. I'm not so sure it matters too much. One of the follow up comments also suggest using 'en_US' instead, which is the same format as java.utils.Locale.toString(). Android hasn't documented this clearly.

[jamsch]

Just a note: iOS locales use the [language designator]_[region designator] syntax so it's probably best keeping 'en_US' as the default.

[Louis-7]

Anyway, we should find a way to notice other developers. Other people may have this issue either.

[sibelius]

better add this to another section of readme