Fix overridable written with an extra 'e'

Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 33ef190..43fa791 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -376,7 +376,7 @@
 		@{$feature{$name}{'default'}});
 	if (!$override) { return @defaults; }
 	if (!defined $sub) {
-		warn "feature $name is not overrideable";
+		warn "feature $name is not overridable";
 		return @defaults;
 	}
 	return $sub->(@defaults);