Customer feedback | az cognitiveservices account identity | missing information | azDO 318916

### Describe the bug

This GitHub issue is being moved from UUF azDO work item [318916](https://dev.azure.com/msft-skilling/Content/_workitems/edit/318916).

### Enginering request

Please provide more information in the reference command subgroup `long-summary` description. Does this command only work to produce a system-assigned identity? Can a customer NOT use a user-assigned managed identity? Unfortunately, there is no conceptual content to fill in this information gap (accoding to [this list of docs](https://learn.microsoft.com/en-us/cli/azure/reference-docs-index?view=azure-cli-latest#az-cognitiveservices)).

### Customer feedback

**Verbatim:**
no instructions on how to associate a user-assigned managed identity to a cognitive services account (formrecognizer allows this)

**Verbatim Id:**
0a654d1b-0b7e-ef11-ac20-000d3a368e63

**Live URL:**
https://learn.microsoft.com/en-us/cli/azure/cognitiveservices/account/identity

**GitHub URL:**
https://github.com/MicrosoftDocs/azure-docs-cli/blob/live/latest/docs-ref-autogen/cognitiveservices/account/identity.yml

### Related command

az cognitiveservices account identity

### Errors

n/a

### Issue script & Debug output

n/a

### Expected behavior

n/a

### Environment Summary

Azure CLI 2.64.0

### Additional context

_No response_