Make paragraphs into the description

[cbliard]

As of pkgr/installer@be447f2, add more new lines to make the paragraph look like the options.

Before:

After:

[cbliard]

I was about to create more pull requests, put maybe it would be simpler to make . insert two newlines instead of 1, so that visually it looks the same in the config file and the dialog description. (replace . by \n\n instead of \n).