Hey, glad you found the relevant docs section :) Do you have any pointers on how to make it less obscure? We certainly want people to find out how to do it easily!
Viewing post in How to use Butler for HTML games?
Actually yes :)
On this page
https://itch.io/docs/butler/pushing.html
Just under "Channel names" headline, another headline "HTML / Playable in browser Games" should do the trick. Also adding this headline to the contents column on the left, under "Pushing builds" could make it even more visible.
So, you always have to specify a channel when pushing with butler, like so:
butler push folder user/game:channel
If your game was previously uploaded via the website, you'll just need to upload it once with butler with a channel name of your choice (that contains 'html5'), delete the old one, and mark the new one as "This file will be played in the browser", and you're all good to go!
The next time you want to upload an upgrade, use the same channel name you just created, and it will update the embed, and distribute patches to itch.io app users. Hope that clarifies things!