doc: Fix cross-reference and toctree on index.rst and about_zephyr.rst

Change-Id: I315a4d90dc2c98062ca84ec01f915bf47d6f15c1
Signed-off-by: Rodrigo Caballero <rodrigo.caballero.abraham@intel.com>
diff --git a/doc/about_zephyr.rst b/doc/about_zephyr.rst
index 302da40..a6537b7 100644
--- a/doc/about_zephyr.rst
+++ b/doc/about_zephyr.rst
@@ -10,7 +10,7 @@
 
 It is designed to be supported by multiple architectures, including
 ARM Cortex-M, Intel x86, and ARC. The full list of supported platforms
-can be found :ref:`here <platform>`.
+can be found :ref:`here <board>`.
 
 Licensing
 *********
diff --git a/doc/index.rst b/doc/index.rst
index c23ec00..0e47d25 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -8,8 +8,9 @@
    :maxdepth: 1
 
    about_zephyr.rst
-   kernel/kernel.rst
    quick_start/quick_start.rst
+   kernel/kernel.rst
+
 
 Developer Guides
 ################