How can you insert suggestions on a PR in Azure Devops?

I found this somewhat recent mention of experimental PR features, and they mentioned the ability to insert and apply suggestions from the PR itself.

That's a feature I've grown very accustomed to with other products, but I'm a bit lost as to how I can access this feature in Azure DevOps in the present day.

Here is what I actually see:

The "Insert a suggestion" option is not for the comments to the changed files.

Basically it is used to suggest changes for the following things in a file:

• A line of content in the file.
• Multiple selected lines of content in the file.
• Any selected content in the file.