Add portuguese language translation

[PhelypeOleinik]

No description provided.

[davidcarlisle]

Thanks this is merged but seems to be missing translation of lesson 09?

[davidcarlisle]

Thank you for working on learnlatex.org translations.
You may have seen already if watching the repository but just a note
to say that we have extended lesson-06 and more-06 to add descriptions
of defining commands with \newcommand and \NewDocumentCommand

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