1. change some directory structure for the build script

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

IPXE/ipxe_mod_code/ipxe-3fe683e/src/build.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+build_bios() {
+    rm -f bin/ipxe.iso
+
+    make -e -k -j 8 bin/ipxe.iso   BIOS_MODE=BIOS
+
+    if ! [ -e bin/ipxe.iso ]; then
+        echo "Failed"
+        exit 1
+    fi
+
+    mkdir -p ./mnt
+    mount bin/ipxe.iso ./mnt
+
+    rm -f ../../../INSTALL/ventoy/ipxe.krn
+    cp -a ./mnt/ipxe.krn ../../../INSTALL/ventoy/ipxe.krn        
+    
+    umount ./mnt > /dev/null 2>&1
+    umount ./mnt > /dev/null 2>&1
+    umount ./mnt > /dev/null 2>&1
+    
+    rm -rf ./mnt
+
+    echo -e "\n===============SUCCESS===============\n"
+}
+
+
+build_bios
+
+