Documentation: git-svn: fix a grammatical error without awkwardness

The way the sentence is currently written, there needs to be an "its",
but this leads to: "however the remote wildcard may be anywhere as long
as it's its own" which is awkward to read.

Instead, this patch fixes he grammar in a simpler way.
Signed-off-by: NWesley J. Landaker <wjl@icecavern.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-svn.txt

@@ -695,7 +695,7 @@ listed below are allowed:
 
 Keep in mind that the '\*' (asterisk) wildcard of the local ref
 (right of the ':') *must* be the farthest right path component;
-however the remote wildcard may be anywhere as long as it's own
+however the remote wildcard may be anywhere as long as it's an
 independent path component (surrounded by '/' or EOL).   This
 type of configuration is not automatically created by 'init' and
 should be manually entered with a text-editor or using 'git-config'.