[trivial] update README.rst (#93)

be-hase · web-flow · commit 5e32f4f111ae · 2018-01-23T15:35:05.000+09:00
diff --git a/README.rst b/README.rst
@@ -258,7 +258,7 @@ https://developers.line.me/en/docs/messaging-api/reference/#error-responses
         print(e.error.details)
 
 Message objects
-~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~
 
 https://developers.line.me/en/docs/messaging-api/reference/#message-objects
 
