Fix git-show man page formatting in the EXAMPLES section

Fix asciidoc markup so that the man page is properly formatted in the
EXAMPLES section.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-show.txt

@@ -48,15 +48,15 @@ git show v1.0.0::
 	Shows the tag `v1.0.0`, along with the object the tags
 	points at.
 
-git show v1.0.0^{tree}::
+git show v1.0.0^\{tree\}::
 	Shows the tree pointed to by the tag `v1.0.0`.
 
-git show next~10:Documentation/README
+git show next~10:Documentation/README::
 	Shows the contents of the file `Documentation/README` as
 	they were current in the 10th last commit of the branch
 	`next`.
 
-git show master:Makefile master:t/Makefile
+git show master:Makefile master:t/Makefile::
 	Concatenates the contents of said Makefiles in the head
 	of the branch `master`.