EDIT: I am sorry, totally missed that this is the topic about comments on version and not for comments inside the app.
Comments on version is still unavailable at the moment.
Comments are already avaialble in PowerApps. For in line comments use :
// add comment here
For multi line comment use:
/* my comment goes here and here and here */
is this ever going to be a functionality? those comment fields just taunt me as I look at version history. I'd like to be able to say, here's where I changed the user input to drop down or here's where I added an experimental logic to the button that is now messing everything up RESTORE BEFORE.
For those looking to comment versions, I just discovered that there is an active idea at https://powerusers.microsoft.com/t5/PowerApps-Ideas/Allowing-a-changelog-or-comment-with-each-saved-... Please join me in upvoting this.