git-svn.txt: fix AsciiDoc formatting error

As asterisks are used to indicate bold text in AsciiDoc, shell glob
expressions must be escaped appropriately.

Signed-off-by: Keshav Kini <keshav.kini@gmail.com>
Signed-off-by: Eric Wong <normalperson@yhbt.net>

Documentation/git-svn.txt

@@ -684,7 +684,7 @@ svn-remote.<name>.noMetadata::
 +
 This option can only be used for one-shot imports as 'git svn'
 will not be able to fetch again without metadata. Additionally,
-if you lose your .git/svn/**/.rev_map.* files, 'git svn' will not
+if you lose your .git/svn/\*\*/.rev_map.* files, 'git svn' will not
 be able to rebuild them.
 +
 The 'git svn log' command will not work on repositories using