Fix API paths in README

[akariv]

No description provided.

[coveralls]

Coverage remained the same at 71.587% when pulling da720e9 on test/pr into 1e346e4 on master.

[rufuspollock]

@akariv note I suggest we move all API docs asap to https://github.com/datahq/docs/blob/master/docs/developers/api.md (we already did a first pass of integrating the README contents 2d ago).

[akariv]

@rufuspollock given that we want these components to be reusable by others, it makes sense to keep relevant docs in the repo itself and not centralised.
Perhaps we could link to the individual READMEs in the separate repos instead?

[rufuspollock]

@akariv let's talk about this on next chat.