az monitor scheduled-query lacks explanations of the acceptable conditions

### Extension name (the extension in question)
az monitor scheduled-query create

### Description of issue (in as much detail as possible)

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[The documentation](https://docs.microsoft.com/en-us/cli/azure/ext/scheduled-query/monitor/scheduled-query?view=azure-cli-latest) shows a `--condition` parameter for the `create` and `update` commands, but the syntax appears to be unique to the az commands, and isn't really explained. What are the acceptable formats of the conditions? How do you do define aggregated conditions? Can you set dynamic thresholds via these commands?