doc/sandbox: improve formatting of command line options

Show the command line options in bold.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/arch/sandbox.rst b/doc/arch/sandbox.rst
index 4674c42..1a7801a 100644
--- a/doc/arch/sandbox.rst
+++ b/doc/arch/sandbox.rst
@@ -99,37 +99,37 @@
 Various options are available, mostly for test purposes. Use -h to see
 available options. Some of these are described below:
 
-* -t, --terminal <arg>
-  - The terminal is normally in what is called 'raw-with-sigs' mode. This means
+-t, --terminal <arg>
+  The terminal is normally in what is called 'raw-with-sigs' mode. This means
   that you can use arrow keys for command editing and history, but if you
   press Ctrl-C, U-Boot will exit instead of handling this as a keypress.
   Other options are 'raw' (so Ctrl-C is handled within U-Boot) and 'cooked'
   (where the terminal is in cooked mode and cursor keys will not work, Ctrl-C
   will exit).
 
-* -l
-  - Show the LCD emulation window.
+-l
+  Show the LCD emulation window.
 
-* -d <device_tree>
-  - A device tree binary file can be provided with -d. If you edit the source
+-d <device_tree>
+  A device tree binary file can be provided with -d. If you edit the source
   (it is stored at arch/sandbox/dts/sandbox.dts) you must rebuild U-Boot to
   recreate the binary file.
 
-* -D
-  - To use the default device tree, use -D.
+-D
+  To use the default device tree, use -D.
 
-* -T
-  - To use the test device tree, use -T.
+-T
+  To use the test device tree, use -T.
 
-* -c [<cmd>;]<cmd>
-  - To execute commands directly, use the -c option. You can specify a single
+-c [<cmd>;]<cmd>
+  To execute commands directly, use the -c option. You can specify a single
   command, or multiple commands separated by a semicolon, as is normal in
   U-Boot. Be careful with quoting as the shell will normally process and
   swallow quotes. When -c is used, U-Boot exits after the command is complete,
   but you can force it to go to interactive mode instead with -i.
 
-* -i
-  - Go to interactive mode after executing the commands specified by -c.
+-i
+  Go to interactive mode after executing the commands specified by -c.
 
 Memory Emulation
 ----------------