The Clan Logs contains 100 lines in total, combined of the latest joins, leavings, promotions, demotions and clan member name changes. To get it follow the steps below.
In your google sheet, look at the bottom left corner and click the add new sheet button.
Then click the arrow pointing down on your newly created sheet and choose Rename...
Name it "Logs" (without the quotes) and you are done.
Next time your google sheet gets updated by the bot, it will populate your Logs sheet too.
If you'd like to be able to keep a Log sheet that's more then 100 lines long you can do so with the Complete Clan Logs Guide.