Add documentation on how to change locale

[gsidhu]

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Tests

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As pointed out in Issue #188, the Getting Started documentation is missing information on how to switch the app locale. This PR adds a tiny snippet to the end of the existing documentation with the relevant code to switch the language.

This should make it easier for new users (like me!) to get started even faster.

[benmccann]

Suggested change

	You can switch the current locale in your app using `locale` –
	You can switch the current locale in your app using `locale.set`: