Add instructions for "Cookie Login" for Bilibili

[NinadKP]

How to log in to Bilibili:

1. Log in to Bilibili.
2. Right Click -> Inspect -> Application -> Cookies-> "https://www.bilibili.com"
3. Copy the values to insert it in this format: "DedeUserID=[insert value]; DedeUserID__ckMd5=[insert value]; sid=[insert value]; SESSDATA=[insert value];"
4. Then put the string without quotes in the cookie login in settings.
5. Check login status to see if you successfully logged in. It should say "登录成功" if you logged in properly. The search is broken for the plugin, so if you put videos in watch later or history, you can access them that way in Kodi.