Documentation: ctype_function should be set for chinese

[ldct]

The following code sample produces poor parse output unless the second last line is uncommented

var RakutenMA = require('./rakutenma');
var fs = require('fs');

var model = JSON.parse(fs.readFileSync("model_zh.json"));
var rma = new RakutenMA(model);
rma.featset = RakutenMA.default_featset_zh;
rma.hash_func = RakutenMA.create_hash_func(15);
var chardic = JSON.parse(fs.readFileSync("zh_chardic.json"))
// rma.ctype_func = RakutenMA.create_ctype_chardic_func(chardic);

console.log(rma.tokenize("下雨了。奶奶望着窗户外边哗哗的大雨，心里很着急。她想：京京带着伞，不要紧。小玲忘了带伞，一定要淋湿了。"));

I think this should be mentioned in the section "Using bundled models to analyze Chinese/Japanese sentences" in the readme.