x86: doc: Move into its own directory

There is enough material that it makes sense to split this up into
several files. Create an x86/ directory for this purpose.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/doc/arch/index.rst b/doc/arch/index.rst
index 2f916f4..60c93b3 100644
--- a/doc/arch/index.rst
+++ b/doc/arch/index.rst
@@ -15,5 +15,5 @@
    riscv
    sandbox/index
    sh
-   x86
+   x86/index
    xtensa
diff --git a/doc/arch/x86/index.rst b/doc/arch/x86/index.rst
new file mode 100644
index 0000000..3dc19d6
--- /dev/null
+++ b/doc/arch/x86/index.rst
@@ -0,0 +1,11 @@
+.. SPDX-License-Identifier: GPL-2.0+ */
+.. Copyright 2023 Google LLC
+.. sectionauthor:: Simon Glass <sjg@chromium.org>
+
+x86
+===
+
+.. toctree::
+   :maxdepth: 2
+
+   x86
diff --git a/doc/arch/x86.rst b/doc/arch/x86/x86.rst
similarity index 99%
rename from doc/arch/x86.rst
rename to doc/arch/x86/x86.rst
index 89d3e7b..8781c16 100644
--- a/doc/arch/x86.rst
+++ b/doc/arch/x86/x86.rst
@@ -696,8 +696,8 @@
   No controllers found
   Hit any key to stop autoboot:  0
 
-See :doc:`../develop/uefi/u-boot_on_efi` and :doc:`../develop/uefi/uefi` for
-details of EFI support in U-Boot.
+See :doc:`../../develop/uefi/u-boot_on_efi` and :doc:`../../develop/uefi/uefi`
+for details of EFI support in U-Boot.
 
 Chain-loading
 -------------
@@ -733,7 +733,7 @@
 To generate SMBIOS tables in U-Boot, for use by the OS, enable the
 CONFIG_GENERATE_SMBIOS_TABLE option. The easiest way to provide the values to
 use is via the device tree. For details see
-:download:`smbios.txt <../device-tree-bindings/sysinfo/smbios.txt>`.
+:download:`smbios.txt <../../device-tree-bindings/sysinfo/smbios.txt>`.
 
 TODO List
 ---------