sd-boot: Add → as alternative to boot selected entry

This is sometimes slightly more convenient to use
and is also what GRUB supports.

man/systemd-boot.xml

@@ -123,6 +123,7 @@
 
       <varlistentry>
         <term><keycap>↵</keycap> (Enter)</term>
+        <term><keycap>→</keycap> (Right)</term>
         <listitem><para>Boot selected entry</para></listitem>
       </varlistentry>
 

src/boot/efi/boot.c

@@ -742,6 +742,7 @@ static BOOLEAN menu_run(
 
                 case KEYPRESS(0, 0, CHAR_LINEFEED):
                 case KEYPRESS(0, 0, CHAR_CARRIAGE_RETURN):
+                case KEYPRESS(0, SCAN_RIGHT, 0):
                         exit = TRUE;
                         break;