Improve document az repos pr create

It seems that the options '--auto-complete' and '--bypass-policy' cannot be used together with `az repos pr create` command. Please call out the specifically in the documentation.

```
ERROR: Invalid argument value.
Parameter name: The bypass option cannot be used with auto-complete.
```

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#### Document Details

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* ID: 1e48ddaa-64b8-e414-7ea9-2746827fcc5f
* Version Independent ID: 952f1742-6d3b-a177-a2e0-164b563c1771
* Content: [az repos pr](https://docs.microsoft.com/en-us/cli/azure/repos/pr?view=azure-cli-latest)
* Content Source: [latest/docs-ref-autogen/repos/pr.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/master/latest/docs-ref-autogen/repos/pr.yml)
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**