Add mastodon sharing link

data/sharing.json

@@ -43,5 +43,10 @@
     "icon": "bluesky",
     "title": "sharing.bluesky",
     "url": "https://bsky.app/intent/compose?text=%[2]s+%[1]s"
-  }
-}
+  }.
+  "mastodon": {
+    "icon": "mastodon",
+    "title": "sharing.mastodon",
+    "url": "https://toot.kytta.dev/?text=%[2]s+%[1]s"
+  }  
+}