decrypt.js 的链接

[sieveLau]

the src link of decrypt.js in hugo_encryptor.py should be replaced with https://cdn.jsdelivr.net/gh/Li4n0/hugo_encryptor@master/decrypt.js, so users don't need to copy it into the static folder.

在已合并的pull request #21 中提到的decrypt.js的链接，由于当时没有merge所以无法生成jsdelivr的cdn链接。merge之后可以生成了，所以为了让用户不用自己复制js到static目录，建议修改script block的src链接。