Add Dendi (ddn)

Requested at
https://translatewiki.net/w/i.php?oldid=11511968#Demande_d'ajout_de_la_langue_Dendi

Autonym from the requested. There are several other
found online, but for simplicity, we can start with
this one now.

data/langdb.yaml

@@ -169,6 +169,7 @@ languages:
   da: [Latn, [EU], dansk]
   dag: [Latn, [AF], dagbanli]
   dar: [Cyrl, [EU], дарган]
+  ddn: [Latn, [AF], dendi]
   de-at: [Latn, [EU], Österreichisches Deutsch]
   de-ch: [Latn, [EU], Schweizer Hochdeutsch]
   de-formal: [Latn, [EU], Deutsch (Sie-Form)]

data/language-data.json

@@ -1005,6 +1005,13 @@
             ],
             "дарган"
         ],
+        "ddn": [
+            "Latn",
+            [
+                "AF"
+            ],
+            "dendi"
+        ],
         "de-at": [
             "Latn",
             [