client.requestOptions() should be documented

[eahutchins]

The README.md should document the requestOptions() API (why does it take two args, for example?) Maybe show an example enabling github's preview API:

client.requestOptions({
   headers: {
      Accept: 'application/vnd.github.she-hulk-preview+json'
   }
});

[pksunkara]

requestOptions() is used by octonode internally. It is not much helpful to the end users.

[eahutchins]

Is there a better way to enable github preview APIs? Mucking with requestDefaults[] directly seems worse...

[pksunkara]

No, you can not modify individual api call request options. At least for now. I am planning to refactor octonode with alpaca