Unclear article

### Type of issue

Missing information

### Description

The whole point of the article in question is how to format the data for NER. It does successfully give the very basics of how to format the Training data, however it completely misses on the Key Information File. How is that suppose to be formatted? Tabs, commas, newline?

As a developer just starting with ML.net, it would also not hurt to have a link to what the definitions or concepts of labels, tokens, entities, etc...

### Page URL

https://learn.microsoft.com/en-us/dotnet/machine-learning/how-to-guides/ner-dataset-guide

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/machine-learning/how-to-guides/ner-dataset-guide.md

### Document Version Independent Id

e5e56fad-4fcc-181d-74a4-0889b4e54dcb

### Article author

@zewditu

### Metadata

* ID: e9d4e704-b7d6-8ed1-b49e-340a4f2db3db
* Service: **dotnet-ml**

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