add ner manual annotator-training recipe

[kabirkhan]

We want a recipe for helping to train annotators for the Global News sTP project.

[magdaaniol]

The idea I had here was to give a bit more elaborate error messages that, minimally, would point the user to the relevant section in the guidelines or, better, provide example-specific explanations. I can think of two ways how to achieve that: 1) provide another json as input to the recipe that would contain the explanations specific to each example 2) store explanations directly in the golden dataset under meta or another key. WDYT?

[magdaaniol]

As for customizing the alert popup, I also need this for another recipe so I'll dig a little / ask around whether it can be achieved easily.

[kabirkhan]

So the UI code just calls alert directly here with a message from the Prodigy API. https://github.com/explosion/prodigy/blob/48636e54e5f38479c8801ee1aa94d2b8affb03cc/app/containers/App.jsx#L311

We do have a Modal component for displaying the instructions so we could adapt that if we'd like.