Fix typo

tsnoam · tsnoam · commit bd96771a7ae9 · 2017-01-07T23:05:58.000+02:00
diff --git a/telegram/bot.py b/telegram/bot.py
@@ -415,7 +415,7 @@ def sendDocument(self,
             chat_id: Unique identifier for the message recipient - Chat id.
             document: File to send. You can either pass a file_id as String to resend a file that
                 is already on the Telegram servers, or upload a new file using multipart/form-data.
-            filename (Optional[str]): File name that shows in telegram message (it is usefull when
+            filename (Optional[str]): File name that shows in telegram message (it is useful when
                 you send file generated by temp module, for example).
             caption (Optional[str]): Document caption (may also be used when resending documents by
                 file_id), 0-200 characters.
