[tldoc] Updated PT-BR translation

[Paulo Roberto Massa Cereda]

Hello friends! :)

Sadly, I might have forgotten to update some messages from the PT-BR 
translation. The current pt_br.po file has 95% of its messages properly 
localized. I tried to redeem myself and updated the file accordingly. 
Now it's back to 100%.

The new file is now available here:
https://github.com/cereda/texlive-ptbr

Out of curiosity, I left the original comment lines (#~) in the .po file 
(I used the pt_br.po version from TL2012). Maybe we could remove those 
lines?

Best wishes,

Paulo