docs: update demo site to build from local

packages/demo/node_modules/.bin/webpack

@@ -0,0 +1,15 @@
+#!/bin/sh
+basedir=$(dirname "$(echo "$0" | sed -e 's,\\,/,g')")
+
+case `uname` in
+    *CYGWIN*) basedir=`cygpath -w "$basedir"`;;
+esac
+
+if [ -x "$basedir/node" ]; then
+  "$basedir/node"  "$basedir/../../../../node_modules/webpack/bin/webpack.js" "$@"
+  ret=$?
+else 
+  node  "$basedir/../../../../node_modules/webpack/bin/webpack.js" "$@"
+  ret=$?
+fi
+exit $ret

packages/demo/node_modules/.bin/webpack.cmd

@@ -0,0 +1,7 @@
+@IF EXIST "%~dp0\node.exe" (
+  "%~dp0\node.exe"  "%~dp0\..\..\..\..\node_modules\webpack\bin\webpack.js" %*
+) ELSE (
+  @SETLOCAL
+  @SET PATHEXT=%PATHEXT:;.JS;=;%
+  node  "%~dp0\..\..\..\..\node_modules\webpack\bin\webpack.js" %*
+)