1. change some directory structure for the build script

2. add build script and document
   see DOC/BuildVentoyFromSource.txt for detail

IPXE/buildipxe.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+rm -rf ipxe-3fe683e
+
+tar -xvf ipxe_org_code/ipxe-3fe683e.tar.bz2 -C ./
+
+rm -rf ./ipxe-3fe683e/src/bin
+rm -rf ./ipxe-3fe683e/src/drivers
+
+/bin/cp -a ipxe_mod_code/ipxe-3fe683e ./
+
+cd ipxe-3fe683e/src
+
+sh build.sh
+
+cd ../../
+