Function expression and arrows

[Tuoris]

Note: given the fact that some words and phrases are yet missing from glossary,
I use following translations (source - MDN 🇺🇦) for them:

• Function Declaration -> Оголошення Функції, left both words capitalized for better clarity and readability
• Function Expression -> Функціональний Вираз, left both words capitalized for the same reason
• expression -> вираз
• strict mode -> суворий режим
• callback -> колбек/функція зворотного виклику, source - Wiki 🇺🇦

Bonus 😆 :

• John -> Микола - most common ukrainian first name according to Internet

[tarasyyyk]

• expression was agreed to translate as вираз. Added to Glossary. Thanks.

• strict mode - not agreed yet: Словосполучення «strict mode» – суворий режим #39

• callback - not agreed yet. Need to create issue and discuss. For me, the both variant are good.

• John - we translate as Іван. Микола will be used for Michael.

[Tuoris]

Good point, @tarasyyyk !

• callback - I feel that колбек and функція зворотного виклику are synonyms and both can be used. Please create an issue if needed (I personally think it's not)
• strict mode - most voted translation is used (few weeks left)
• John - sure, I'll change Микола -> Іван (yet russian version uses Вася) )

Edit: fix typo

[CLAassistant]

All committers have signed the CLA.

[tarasyyyk]

Great job! There are a lot of text and no any major mistakes. This is the first such pull request!
Some translation even better that english source text (I mean Error => ReferenceError).

[tarasyyyk]

@all-contributors add @Tuoris for translation.

[allcontributors]

@tarasyyyk

I've put up a pull request to add @Tuoris! 🎉