Documentation: Fix ssh://[user@]host.xz URL

Earlier commit c3f17061 broke asciidoc markup.

Noticed by Alp Toker with a fix, but fixed up in a way with smaller
formatting impact.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/urls.txt

@@ -10,9 +10,9 @@ to name the remote repository:
 - https://host.xz/path/to/repo.git/
 - git://host.xz/path/to/repo.git/
 - git://host.xz/~user/path/to/repo.git/
-- ssh://[user@]host.xz/path/to/repo.git/
-- ssh://[user@]host.xz/~user/path/to/repo.git/
-- ssh://[user@]host.xz/~/path/to/repo.git
+- ssh://+++[user@+++]host.xz/path/to/repo.git/
+- ssh://+++[user@+++]host.xz/~user/path/to/repo.git/
+- ssh://+++[user@+++]host.xz/~/path/to/repo.git
 ===============================================================
 
 SSH Is the default transport protocol and also supports an