Add numeric fused head dataset
> Thanks for adding this @ghomasHudson!
> I added some comments for some of the fields.
> 
> Also, I'm not sure about this since I haven't used the library yet, but maybe it's worth adding the identification and resolution as two separate datasets?

Thanks for replying @yanaiela - I hope this will make your dataset more accessible to a wider audience - I've added the changes to the model card you suggested.

In terms of the identification and resolution tasks, I've currently added them as separate `splits` in huggingface/datasets so you can load identification like this:

```
import datasets
dataset = datasets.load_dataset("numeric_fused_head", "identification")
print(dataset["train"][0])
>> {"tokens": ["The", "quick", "brown", "fox",....], "start_index": 11, "end_index": 12, "label": 0}
```
And resolution like this:

```
import datasets
dataset = datasets.load_dataset("numeric_fused_head", "resolution")
print(dataset["train"][0])
>> {"tokens": ["The", "quick", "brown", "fox",....], "head": ["AGE"], "anchors_indices": [12], ...}
``` I hope so too, thanks!

Re the splits, that makes sense to me.
Adding the [NFH: Numeric Fused Head](https://nlp.biu.ac.il/~lazary/fh/) dataset.

Everything looks sensible and I've included both the identification and resolution tasks. I haven't personally used this dataset in my research so am unable to specify what the default configuration / supervised keys should be.

I've filled out the basic info on the model card to the best of my knowledge but it's a little tricky to understand exactly what the fields represent.

Dataset author: @yanaiela 