Make Minor Improvement to Grammar on Nullish coalescing operator '??' Lesson

In the lesson titled Nullish coalescing operator '??', in the Comparison with II section, located here, there is a minor mistake in the grammar.

"Historically, the OR || operator was there first. It exists since the beginning of JavaScript, so developers were using it for such purposes for a long time."

Should become something like

"Historically, the OR || operator was there first. It's existed since the beginning of JavaScript, so developers were using it for such purposes for a long time."

or

"Historically, the OR || operator was there first. It's been there since the beginning of JavaScript, so developers were using it for such purposes for a long time."

Thank you for these excellent lessons. This is my first attempt to contribute something to a project via Github, I hope it's formatted properly.

Abra a lição sobre o operador Nullish coalescing '??' e vá para a seção Comparison with || vinculada na issue. Revise a frase que começa com “Historically, the OR || operator was there first,”, escolha uma substituição gramaticalmente correta e confirme que a lição exibe a redação revisada.