changed dash to underscore

Author: kristofvc

reference/forms/types/language.rst

@@ -9,7 +9,7 @@ to select from a large list of languages. As an added bonus, the language names
 are displayed in the language of the user.
 
 The "value" for each language is the *Unicode language identifier* used in the `International Components for Unicode`_
-(e.g. ``fr`` or ``zh-Hant``).
+(e.g. ``fr`` or ``zh_Hant``).
 
 .. note::
 
@@ -107,4 +107,4 @@ The actual default value of this option depends on other field options:
 
 .. include:: /reference/forms/types/options/required.rst.inc
 
-.. _`International Components for Unicode`: http://site.icu-project.org
+.. _`International Components for Unicode`: http://site.icu-project.org