i18n: branch: mark option description for translation

Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/branch.c b/builtin/branch.c
index 7df0543..d5d93a8 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -657,7 +657,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		OPT_SET_INT( 0, "set-upstream",  &track, N_("change upstream info"),
 			BRANCH_TRACK_OVERRIDE),
 		OPT_STRING('u', "set-upstream-to", &new_upstream, N_("upstream"), N_("change the upstream info")),
-		OPT_BOOL(0, "unset-upstream", &unset_upstream, "Unset the upstream info"),
+		OPT_BOOL(0, "unset-upstream", &unset_upstream, N_("Unset the upstream info")),
 		OPT__COLOR(&branch_use_color, N_("use colored output")),
 		OPT_SET_INT('r', "remotes",     &filter.kind, N_("act on remote-tracking branches"),
 			FILTER_REFS_REMOTES),