@Grant Yu , you could try the following steps to include a folder with a txt file in your clickonce app.
First, Please set the txt file like the following:
Second, Please right click your app and choose Publish.
Third, Please choose clickonce and click Next until you see Settings page.
Fourth, Please choose Application Files ->click show all files ->change Publish Status to Include->click ok.
Finally, Please click finish to publish the app.
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