Deploy previews

[ghost]

Will deploy previous be making a comeback? I found them quite helpful as, for me, it's difficult to visualize changes in markdown format.

edit: actually, the ability to serve the site locally is even better tbh

[jonaharagon]

This is already implemented. Existing PRs should merge the changes from main into their branch to get them to work, but otherwise they will show up in the future as they did before.