board: starfive: support Pine64 Star64 board

Add documentation files

Signed-off-by: Henry Bell <dmoo_dv@protonmail.com>
Cc: ycliang@andestech.com
Cc: heinrich.schuchardt@canonical.com
Reviewed-by: E Shattow <lucent@gmail.com>
diff --git a/doc/board/starfive/index.rst b/doc/board/starfive/index.rst
index d369b98..72ab6dd 100644
--- a/doc/board/starfive/index.rst
+++ b/doc/board/starfive/index.rst
@@ -8,4 +8,5 @@
 
    milk-v_mars
    milk-v_mars_cm
+   pine64_star64
    visionfive2