The PHP Manual is translated into several languages, but this process requires humans to constantly update each language.
A few steps must be taken before working on a translation.
And since this document is not complete, please read the official HOWTO on this topic:
Also, read the HOWTO for additional information, like how to download the documentations source from CVS.
This is an easy step for several languages, but not for those that are considered outdated. A few places to look:
The mailing list. Each translation has its own mailing list that receives both commits and discussion. The lists will show up as php.doc.{lang} below, whereas the mailing address is doc-{lang}@lists.php.net where {lang} is the appropriate country/language code.
Several tools/scripts exist within the documentation files that help out finding errors and/or information related to the translation. The output of these scripts are also online:
Send an email to the translations list and introduce yourself. If you're interested in translating a certain section, say so, or ask for suggestions. While writing this introduction, also send a copy to the main documentation list (phpdoc@lists.php.net).
The main documentation HOWTO discusses working on the English version, but a few translation specific notes are worth mentioning here: