Added translation to spanish of sections 3, 3.1 and 3.1.1 including a small correction in the English paper

[nelruk]

The translations were made with proper links, images, and formatting, improving the use of CO2 to CO², using <sup> both English paper and Spanish draft-paper

[medied]

Actually, silly me, I should have reviewed more thoroughly before merging: is the correct chemical formula written using sup or sub?

https://www.wikiwand.com/en/Carbon_dioxide https://developer.mozilla.org/en-US/docs/Web/HTML/Element/sub

Looks like we got our carbon dioxide wrong. @nelruk can I double check with you? We could make a new PR to make this small change.

[medied]

Fixed to CO₂ with 9c9acd6ca164fc1a32de825054a03db7a4d88ce9

[nelruk]

Now I saw the issue, you're right @medied thanks for the correction. I didn't realize put the number in the wrong direction.