[PATCH 4/4] Documentation: lto: add LTO documentation to toc index

[Bagas Sanjaya]

kernel test robot reported toctree warning:

Documentation/kbuild/lto-build.rst: WARNING: document isn't included in any toctree

Add LTO documentation (lto-build.rst) to kbuild table of contents.

Link: https://lore.kernel.org/linux-doc/202207161100.lCdR6Unx-lkp@xxxxxxxxx/
Fixes: 0350b4dd55922f ("Kbuild, lto: Add Link Time Optimization support")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx>
---
 Documentation/kbuild/index.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/kbuild/index.rst b/Documentation/kbuild/index.rst
index cee2f99f734b5a..1937eee7c43705 100644
--- a/Documentation/kbuild/index.rst
+++ b/Documentation/kbuild/index.rst
@@ -22,6 +22,8 @@ Kernel Build System
     gcc-plugins
     llvm
 
+    lto-build
+
 .. only::  subproject and html
 
    Indices
-- 
An old man doll... just what I always wanted! - Clara