Updated translator request

The request for volunteer translators has been altered. I specified that language codes have to be from the ISO 639-1 specification, and added a link to Wikipedia listing all of them. I also changed the vocabulary request to use the vocabulary.xml file from the 'develop' branch, because it will, in all cases, be more recent; and for consistency I changed the slashes and formatting of the directory name where the translated vocabulary.xml file should be placed.

README.md

@@ -84,10 +84,10 @@ If you are multi-lingual, and wish to assist this project by volunteering transl
 
 If you wish to submit a translation as a pull request, please use Android Studio's built-in Translations Editor. 
 
-If you don't wish to go through the hassle of installing Android Studio, you can use [this strings.xml file](https://gist.github.com/theblackwidower/206876858d2bc5a81f9014267750d8fd) as a template, and place it in a new directory called `/app/src/main/res/values-xx/` where `xx` is the language's locale code. The various string tags contain elements that need to be translated. Be sure to place the name of the language you're translating as well as your own name, in the field marked `translator_credit`. You can also place the URL to your GitHub, Twitter, or other social media profile or personal/professional website in the field marked `translator_credit_url`.
+If you don't wish to go through the hassle of installing Android Studio, you can use [this strings.xml file](https://gist.github.com/theblackwidower/206876858d2bc5a81f9014267750d8fd) as a template, and place it in a new directory called `/app/src/main/res/values-[language code]/` with the [ISO 639-1 language code](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes). The various string tags contain elements that need to be translated. Be sure to place the name of the language you're translating as well as your own name, in the field marked `translator_credit`. You can also place the URL to your GitHub, Twitter, or other social media profile or personal/professional website in the field marked `translator_credit_url`.
 
 If you don't wish to bother with pull requests, using the template listed above you can also submit your translation through email to [[email protected]](mailto:[email protected]?subject=KanaQuiz%20Translation), with the subject "KanaQuiz Translation".
 
-I'll also ask, if possible, for any translators to also update the [vocabulary.xml](https://github.com/theblackwidower/KanaQuiz/blob/master/app/src/main/res/xml/vocabulary.xml) file by replacing the English answers with answers in their own language, and insert it into a language-specific directory (app\src\main\res\xml-[language code]), so it'll be automatically included as part of the translation package.
+I'll also ask, if possible, for any translators to also update the [vocabulary.xml](https://github.com/theblackwidower/KanaQuiz/blob/develop/app/src/main/res/xml/vocabulary.xml) file by replacing the English answers with answers in their own language, and insert it into a language-specific directory (`app/src/main/res/xml-[language code]/`), so it'll be automatically included as part of the translation package.
 
 If you require any assistance, please do not be afraid to email me. I appreciate the assistance from anyone wishing to volunteer their skills to help with this project.