[PATCH 4/6] README: sandbox: Change reference to sandbox details

[Naoki Hayama]

doc/arch/index.rst is a list of links to each architecture.
As for the sandbox details, doc/arch/sandbox.rst looks better.

Signed-off-by: Naoki Hayama <naoki.hayama at lineo.co.jp>
---

 README | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README b/README
index e8d7df21fb..02cfe45aa6 100644
--- a/README
+++ b/README
@@ -210,7 +210,7 @@ board. This allows feature development which is not board- or architecture-
 specific to be undertaken on a native platform. The sandbox is also used to
 run some of U-Boot's tests.
 
-See doc/arch/index.rst for more details.
+See doc/arch/sandbox.rst for more details.
 
 
 Board Initialisation Flow:
-- 
2.17.1