Outdated README documentation

[merlos]

Hi,

It seems that there is a newer version of the API and now the API returns a numeric application_id instead of the dpg code.

# Now
{
        "id": "10003",
        "name": "AccessMod",
        ...
}

# Earlier
 {
    "id": "accessmod",
    "name": "AccessMod",
    ...
}

Also, seems the former API is kept as https://apiv0.digitalpublicgoods.net/

In addition, the new API does not seem to return all the records (f.i. I cannot find "Oky" on the response text.... I guess it may be paginated now?

An updated version of the README / Documentation to reflect these changes/updates would be appreciated.

Also, it good be nice to learn about the future support for the v0 version of the API.

Thanks!