[#2220] Empty cell in UG

[logical-1985516]

Fixes #2220

Proposed commit message

As branches are already specified in the first cell, the 2nd cell
specifying the branch may only confuse the user.

Let's remove the contents of the second cell.

Other information

Due to intellij recognizing a pipe operator as a column separator, the preview looks different compared to the rendering on github.
Before:

After:

[jonasongg]

LGTM!