ModelBuilder NER is badly described

### Type of issue

Missing information

### Description

I try to make it work, but there is no example and the modelbuilder crashes when using these files:

keyinfo.txt
B-LOC
B-ORG
B-OTH
B-PER
I-LOC
I-ORG
I-OTH
I-PER
B-DATE
O

training.csv
John lives in Berlin O O O B-PER
Microsoft was founded in 1975 B-ORG O O O B-DATE

### 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

### Platform Id

5e58c5fd-e2a3-21f0-e1b7-7f23d07c8c98

### Article author

@zewditu

### Metadata

* ID: e9d4e704-b7d6-8ed1-b49e-340a4f2db3db
* PlatformId: 5e58c5fd-e2a3-21f0-e1b7-7f23d07c8c98
* Service: **dotnet-ml**

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