Update is-is.all.json

Creating some new words on the spot for completeness

translations/is-is.all.json

@@ -169,7 +169,7 @@
   },
   {
     "id": "toggle_navigation",
-    "translation": "Toggle navigation"
+    "translation": "Stilla flakkara af/á"
   },
   {
     "id": "upload",