Added bottom margin to CLI instructions

The CLI instructions block in the empty project page is missing a margin-bottom style property. I added it, you can review the only line I edited to add this.

This only fixes a UX bug (to me), related to the "Remove project" button that is not correctly padded. Now I believe that part look better :)

I attach screenshots.

### before
![Selezione_009](/uploads/f46b2a26c192a0b1994ff2f037f50e6c/Selezione_009.png)

### after
![Selezione_008](/uploads/33a9451bbe8bfd9abd300f9c6eb4005f/Selezione_008.png)

See merge request !3505