Documentation: x86: convert x86_64/uefi.txt to reST

This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/x86/x86_64/index.rst

@@ -8,3 +8,4 @@ x86_64 Support
    :maxdepth: 2
 
    boot-options
+   uefi

Documentation/x86/x86_64/uefi.rst

@@ -1,5 +1,8 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================================
 General note on [U]EFI x86_64 support
--------------------------------------
+=====================================
 
 The nomenclature EFI and UEFI are used interchangeably in this document.
 
@@ -14,29 +17,42 @@ with EFI firmware and specifications are listed below.
 
 3. x86_64 platform with EFI/UEFI firmware.
 
-Mechanics:
+Mechanics
 ---------
-- Build the kernel with the following configuration.
+
+- Build the kernel with the following configuration::
+
 	CONFIG_FB_EFI=y
 	CONFIG_FRAMEBUFFER_CONSOLE=y
+
   If EFI runtime services are expected, the following configuration should
-  be selected.
+  be selected::
+
 	CONFIG_EFI=y
 	CONFIG_EFI_VARS=y or m		# optional
+
 - Create a VFAT partition on the disk
 - Copy the following to the VFAT partition:
+
 	elilo bootloader with x86_64 support, elilo configuration file,
 	kernel image built in first step and corresponding
 	initrd. Instructions on building elilo	and its dependencies
 	can be found in the elilo sourceforge project.
+
 - Boot to EFI shell and invoke elilo choosing the kernel image built
   in first step.
 - If some or all EFI runtime services don't work, you can try following
   kernel command line parameters to turn off some or all EFI runtime
   services.
-	noefi		turn off all EFI runtime services
-	reboot_type=k	turn off EFI reboot runtime service
+
+	noefi
+		turn off all EFI runtime services
+	reboot_type=k
+		turn off EFI reboot runtime service
+
 - If the EFI memory map has additional entries not in the E820 map,
   you can include those entries in the kernels memory map of available
   physical RAM by using the following kernel command line parameter.
-	add_efi_memmap	include EFI memory map of available physical RAM
+
+	add_efi_memmap
+		include EFI memory map of available physical RAM