Update Hallucination README.md

[klshuster]

Patch description
Per #3872, we should include the --model-file parameter in the example training commands for the Hallucination project

[jianguoz]

Patch description
Per #3872, we should include the --model-file parameter in the example training commands for the Hallucination project

Per #3881 and #3873. In #3881, the model should immediately raise an AssertionError when there are NaN instead of logging errors and/or replacing NaN with other values. Besides, after careful investigation, I found the NaN error is not caused by either --indexer-type exact or --indexer-type compressed. The error comes from num_shards if the passages file format meets requirements and there are no repeated entries. Where if end_idx<n_docs, it will raise NaN error. So it is better to set --num-shards to small values. For example, if --shard-id is 0, then --num-shards is a value < int(len(rows of the passages file)/(n_maximum_passages_you_want_to_retrieve-1)). I had slightly updated the readme also to give more instructions.

[klshuster]

Hi @jianguoz, though I appreciate the changes you have proposed, these seem more suitable for a separate PR (as now I cannot actually review the changes you've made)

[jianguoz]

Hi @jianguoz, though I appreciate the changes you have proposed, these seem more suitable for a separate PR (as now I cannot actually review the changes you've made)

@klshuster Sure! I will do it:).

[spencerp]

lgtm!