Provide index.d.ts

[sergatgh]

Hello @akiomik , Please, provide declarations file for the package. It will be handy to use your library in TypeScript.

Links:

• Default chrome declarations - as an example;
• Official Typescript Manual - you'll probably will need to provide path to declarations like this:

{... , 
"types" : "index.d.ts", 
... }

Regards.