[syslinux] keeppxe - documentation recommendation

[Miguel]

Summary
=======

I have a recommendation for a minor documentation change regarding 'keeppxe'.

I lost some time on this and think that a clarification could save other
people time in the future.

pxelinux.doc should be tweaked to explicitly say that the "keeppxe" option
should be given on the kernel command line through the APPEND statemen


Detail
======

pxelinux.doc line 356 says:

If the option "keeppxe" is given on the kernel command line, PXELINUX will
keep the PXE and UNDI stacks in memory.

I interpreted this to mean that 'keeppxe' should go after 'kernel' in my
configuration file ... as in:

INCORRECT EXAMPLE
-----------------
label foo
  kernel memdisk keeppxe
  append initrd=/freedos/fd2880.img


I then spent a few hours trying to figure out why things were not working.

In fact, the 'keeppxe' needs to be added to the kernel command line as
part of the 'append' statement, as in:

CORRECT EXAMPLE
---------------
label foo
  kernel memdisk
  append initrd=/freedos/fd2880.img keeppxe


As with many things, in hindsight it was obvious.

I recommend that pxelinux.doc be amended to explicitly say that the
'keeppxe' parameter gets added to the kernel command line using the APPEND
directive ... something like:

If the option "keeppxe" is passed to the kernel command line using the
APPEND statement, PXELINUX will keep the PXE and UNDI stacks in memory.


Miguel