Documentation/git-cat-file.txt: add missing line break

Without [verse], the line break between the two synopsis lines does
not make it into the man page.
Signed-off-by: NLea Wiemann <LeWiemann@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-cat-file.txt

@@ -8,6 +8,7 @@ git-cat-file - Provide content or type/size information for repository objects
 
 SYNOPSIS
 --------
+[verse]
 'git-cat-file' [-t | -s | -e | -p | <type>] <object>
 'git-cat-file' [--batch | --batch-check] < <list-of-objects>