Added README.de-DE.md

.all-contributorsrc

@@ -4,7 +4,8 @@
     "README.zh-CN.md",
     "README.ru-RU.md",
     "README.ko-KR.md",
-    "README.it-IT.md"
+    "README.it-IT.md",
+    "README.de-DE.md"
   ],
   "imageSize": 100,
   "commit": false,