[PATCH] Documentation: update for loongson1 board

[Du Huanpeng]

Hi,
> 
> I already applied this version before you sent v2, but as far as I can
> see only the commit message has changed, right?
Hi, only commit message changed. :)

by the way, what happen to these targets:
  zbarebox.bin
  zbarebox

are all broken with these defconfigs
  ath79_defconfig
  xburst_defconfig
  loongson-ls1b_defconfig

--8<----
  LDS     arch/mips/pbl/zbarebox.lds
  LZO     arch/mips/pbl/piggy.lzo
  AS      arch/mips/pbl/piggy.lzo.o
  LD      arch/mips/pbl/zbarebox
arch/mips/pbl/zbarebox.lds:5: undefined symbol `MALLOC_BASE' referenced in expression
/home/du/o/barebox/arch/mips/pbl/Makefile:38: recipe for target 'arch/mips/pbl/zbarebox' failed
make[1]: *** [arch/mips/pbl/zbarebox] Error 1
/home/du/o/barebox/arch/mips/Makefile:114: recipe for target 'zbarebox' failed
make: *** [zbarebox] Error 2
--8<---

Du Huanpeng