Add section on documentation translations

docs/styleguide.md

@@ -27,6 +27,21 @@ These are the ways that we construct the Electron documentation.
  - ```### `method(foo, bar)` _OS X_```
 - Prefer 'in the ___ process' over 'on'
 
+### Documentation Translations
+
+Translations of the Electron docs are located within the `docs-translations`
+directory.
+
+To add another set (or partial set):
+
+- Create a subdirectory named by language abbreviation.
+- Within that subdirectory, duplicate the `docs` directory, keeping the
+  names of directories and files same.
+- Translate the files.
+- Update the `README.md` within your language directory to link to the files
+  you have translated.
+- Add a link to your translation directory on the main Electron [README](https://github.com/atom/electron#documentation-translations).
+
 ## Reading Electron Documentation
 
 Here are some tips for understanding Electron documentation syntax.