pt_BR.ISO8859-1/articles/new-users: converted to .po

• content synchronized with en_US document (rev 52136)
• article.xml converted to .po
• .po file was translated to pt_BR
• .po and .xml file has been set to UTF-8 encoding
• information about volunteers who translated and/or revised the document was added to the header of the .po file.

Reviewed by: dbaio
Approved by: gabor (mentor, implicit)
Obtained from: The FreeBSD Brazilian Portuguese Documentation Project
Differential Revision: https://reviews.freebsd.org/D16969