Needs link to timespan definition

The az monitor log-analitics query documentation makes reference to specifying a timespan. It even offers an example of a specifying one, but the timespan specification is not obvious at all. A link to a reference documentation of the format of the timespan string would be very useful here.
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* ID: 56af75a3-3b2f-711b-21b3-57375fbe124d
* Version Independent ID: 93d7d728-534e-3e1e-e138-bcaf040ebd2d
* Content: [az monitor log-analytics](https://learn.microsoft.com/en-us/cli/azure/monitor/log-analytics?view=azure-cli-latest)
* Content Source: [latest/docs-ref-autogen/monitor/log-analytics.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/main/latest/docs-ref-autogen/monitor/log-analytics.yml)
* Service: **monitoring-and-diagnostics**
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**