addCustomFieldOption - needs to be postAsBody

[andykirk]

Hi,
I was trying to add an option to a dropdown and it doesn't work as-is.
The docs (https://developers.trello.com/v1.0/reference#customfieldsidoptions-2) seem incomplete and inaccurate.

The value needs to be sent as json body, similar to e13cdab but for POST not PUT.

I actually got this working in Postman (Chrome extension) by inspecting the Network requests Trello itself when I manually completed the action I want use the API for. Note I had to use https://trello.com NOT https://api.trello.com, so I don't know what's going on there :-(

Cheers

[andykirk]

#31