x86: Add a command to display coreboot sysinfo

This information is interesting to look at and can be important for
debugging and inspection. Add a command to display it in a helpful
format.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index 35c515f..fb83434 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -21,6 +21,7 @@
    booti
    bootmenu
    button
+   x86/cbsysinfo
    conitrace
    echo
    exception
diff --git a/doc/usage/x86/cbsysinfo.rst b/doc/usage/x86/cbsysinfo.rst
new file mode 100644
index 0000000..8c03a85
--- /dev/null
+++ b/doc/usage/x86/cbsysinfo.rst
@@ -0,0 +1,25 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+cbsysinfo
+=========
+
+Synopis
+-------
+
+::
+
+    cbsysinfo
+
+
+Description
+-----------
+
+This displays information obtained from the coreboot sysinfo table. It is only
+useful when booting U-Boot from coreboot.
+
+Example
+-------
+
+::
+
+    => cbsysinfo