Add GFM test case

Author: mzlogin

test/GFM.md

@@ -1,5 +1,6 @@
 
 <!-- vim-markdown-toc GFM -->
+
 * [heading1](#heading1)
     * [heading2](#heading2)
 * [chapter 1](#chapter-1)
@@ -12,6 +13,7 @@
     * [1.1 heading with dot 2.1](#11-heading-with-dot-21)
     * [1.1](#11)
         * [heading with some "special" (yes, special) chars: les caractères unicodes](#heading-with-some-special-yes-special-chars-les-caractères-unicodes)
+    * [heading with Cyrillic Б б](#heading-with-cyrillic--)
 
 <!-- vim-markdown-toc -->
 
@@ -50,3 +52,5 @@ not heading2
 ## 1.1
 
 ### heading with some "special" (yes, special) chars: les caractères unicodes
+
+## heading with Cyrillic Б б