Update default value in docs and changelog

CHANGES.md

@@ -3,6 +3,8 @@
 ## 5.0.1 (Unreleased)
 
 - Add a new GUI for moderator actions. You can trigger it by entering `/modtools` in a MUC.
+- Reconnect if the server doesn't respond to a `ping` within 10 seconds.
+- Don't query for MAM MUC messages before the cached messages have been restored (another cause of duplicate messages).
 
 ## 5.0.0 (2019-08-08)
 

docs/source/configuration.rst

@@ -1163,7 +1163,7 @@ Use OMEMO encryption by default when the chat supports it.
 ping_interval
 -------------
 
-* Default:  ``180``
+* Default:  ``60``
 
 Make ping to server in order to keep connection with server killing sessions after idle timeout.
 The ping are sent only if no messages are sent in the last ``ping_interval`` seconds