Monitors and connections should document template variables

[mccartney]

In sumologic_monitor resources you can use special variables, e.g. {{NumQueryResults}}. It's hard to guess their names.

They should:

• either be documented inline at https://registry.terraform.io/providers/SumoLogic/sumologic/latest/docs/resources/monitor
• or at least a link to https://help.sumologic.com/Visualizations-and-Alerts/Alerts/Monitors/Template_Variables should be provided

=====

Similarly when using sumologic_connection it's hard to guess all the variables one can use: {{SearchQueryUrl}} or {{TimeRange}}. They should be documented too.