Add dts files

[juji]

Adding dts files so typescript doesn't throw tantrum.

In the future, when updating, you can always create dts file using the provided script:

npm run types

[zellwk]

Just want to let you know that I love this, @juji. I don't really know about typescript and this is super helpful. Can you let me know once you're done with the commits?

[juji]

Thank you @zellwk this is a nice interface for fetch. I like it. Ready to be merged

[SteffQing]

Please merge this, lolz
Discovered ky but forgot the name, and in searching keywords, I discovered this lib
But I am hindered by typescript type checks
So, this is an important update @zellwk
Good work @juji Huge respects

[zellwk]

@juji thanks for the work. Give me a few days to sort out things on my plate and I’ll merge this.

[juji]

Thanks again.. @zellwk

I forgot to remove options.body for GET, DELETE, also removed options.method from named function