This is a request for enhancement. Could you please include a changelog under the Help menu point of the app?
Although I really want to see such feature as well, until recently I thought the changelog is not available anywhere... and then I discovered this page. Better than nothing 😉
I think we decided to use the releases tab here as well with the next release..
Release Notes are also shared at https://medium.com/@wireupdates. We plan to link to these from the menu as you suggested.
There's a link to Wire releases in the About Wire screen. Also with each update you will see an Update banner with link to latest changelog.

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Release Notes are also shared at https://medium.com/@wireupdates. We plan to link to these from the menu as you suggested.