Fixed environment variable name

[oceanapplications]

No description provided.

[addisonlynch]

Probably should have stuck with the previous naming convention using _API_KEY as the suffix. @bashtage will likely decide if this should change given that the current convention is now merged into dev but has not been released. Either IEX_API_TOKEN or IEX_API_KEY works regardless.

However, use of this package does not require the publishable token and the value does not need to be set for the documentation, as a key will be added to the travis environment, in which the documentation is built by doctr.

Thanks!

[bashtage]

Could you fix it in what's new as well?

[bashtage]

Thanks.