Fixing a little misspelling

It is supposed to be DownloadThread() not DownloadTead()

Author: aktasfatih

examples/thread_download.py

@@ -66,6 +66,6 @@ def save(self):
     InstagramAPI = InstagramAPI("login", "password")
     InstagramAPI.login()
 
-    inst = DownloadThead(InstagramAPI, thread_id)
+    inst = DownloadThread(InstagramAPI, thread_id)
     inst.download()
     inst.save()