Update the documentation to include the presense and use case of
modules.builtin.alias.

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Allen Webb <allenwebb@google.com>
---
 Documentation/kbuild/kbuild.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst
index 5202186728b4..b27c66c3ca9e 100644
--- a/Documentation/kbuild/kbuild.rst
+++ b/Documentation/kbuild/kbuild.rst
@@ -17,6 +17,13 @@ modules.builtin
 This file lists all modules that are built into the kernel. This is used
 by modprobe to not fail when trying to load something builtin.
 
+modules.builtin.alias
+---------------------
+This file lists all match-id based aliases for modules built into the kernel.
+An example usage of the built-in aliases is to enable software such as
+USBGuard to allow or block devices outside of just the vendor, product, and
+device ID. This enables more flexible security policies in userspace.
+
 modules.builtin.modinfo
 -----------------------
 This file contains modinfo from all modules that are built into the kernel.
-- 
2.39.2