Add info about rate limit to Readme

[matsuobasho]

I'd like to download multi-year outputs for multiple sites. I'm getting a rate limit and it would be useful to understand what the actual rate threshold is and also potential workarounds.

[jreadey]

By default the NREL gateway is limited to 1000 requests / hour. You can ask NREL for the rate limit to be increased for your api key.

Alternatively, you can run your script from HDF Lab: https://www.hdfgroup.org/hdfkitalab/. or setup your own server in the AWS us-west-2 region. See: https://github.com/HDFGroup/hsds.

[ryancoe]

Hi @jreadey - Who at NREL should we ask about increasing limits for our api keys?

[jreadey]

Hey @ryancoe - there's a contact us to increase the rate limit on this page; https://developer.nrel.gov/docs/rate-limits.