Adds portuguese language & @ symbols

[auyer]

This PR adds the Portuguese language

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (f701be4) to head (d353393).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #79 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 2 2 Lines 119 121 +2 ========================================= + Hits 119 121 +2 ``` | [Files](https://app.codecov.io/gh/gosimple/slug/pull/79?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=gosimple) | Coverage Δ | | |---|---|---| | [languages\_substitution.go](https://app.codecov.io/gh/gosimple/slug/pull/79?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=gosimple#diff-bGFuZ3VhZ2VzX3N1YnN0aXR1dGlvbi5nbw==) | `100.00% <ø> (ø)` | | | [slug.go](https://app.codecov.io/gh/gosimple/slug/pull/79?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=gosimple#diff-c2x1Zy5nbw==) | `100.00% <100.00%> (ø)` | |

[IamNator]

Reviewed PR and confirmed that the following substitutions for Portuguese are correct: '&' -> 'e', '@' -> 'em'. Also verified the following language abbreviations: 'pt', 'prt', 'pt-br', 'por'. No further issues found.

"pt" is the ISO 639-1 language code for Portuguese. "prt" is another abbreviation used for Portuguese, which is derived from the three-letter ISO 639-2 code for the language. "pt-br" is the language code used for Brazilian Portuguese, which is a variation of the Portuguese language spoken in Brazil. "bra" is not a commonly used abbreviation for Portuguese. However, it could be an abbreviation for Brazil, which is a country where Portuguese is the official language. "por" is a three-letter ISO 639-2 code for Portuguese, which is used to represent the language in various contexts.

[IamNator]

Reviewed PR and confirmed that the following substitutions for Portuguese are correct: '&' -> 'e', '@' -> 'em'. Also verified the following language abbreviations: 'pt', 'prt', 'pt-br', 'por'. No further issues found.

'&' is commonly substituted by "e" in Portuguese, which means "and" in English.

'@' is usually substituted by "em" in Portuguese, which means "in" or "on" in English.

[matrixik]

Thank you for this and sorry it took so long.