git-svn.txt: make formatting more consistent.

- correctly link paragraphs within list items
- consistently format examples
- put option alernatives on separate lines
- always use [verse] for config items
- always indent 1st paragraph of a list item, with a tab

Signed-off-by: Yann Dirson <ydirson@altern.org>
Acked-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>