removes text about alert messages supporting variables (#25622)

fixes #25605

docs/sources/alerting/create-alerts.md

@@ -71,7 +71,7 @@ avg() OF query(A, 15m, now) IS BELOW 14
 
 The query used in an alert rule cannot contain any template variables. Currently we only support `AND` and `OR` operators between conditions and they are executed serially.
 For example, we have 3 conditions in the following order:
-*condition:A(evaluates to: TRUE) OR condition:B(evaluates to: FALSE) AND condition:C(evaluates to: TRUE)*
+_condition:A(evaluates to: TRUE) OR condition:B(evaluates to: FALSE) AND condition:C(evaluates to: TRUE)_
 so the result will be calculated as ((TRUE OR FALSE) AND TRUE) = TRUE.
 
 We plan to add other condition types in the future, like `Other Alert`, where you can include the state of another alert in your conditions, and `Time Of Day`.
@@ -95,21 +95,21 @@ So as you can see from the above scenario Grafana will not send out notification
 
 Below are conditions you can configure how the rule evaluation engine should handle queries that return no data or only null values.
 
-No Data Option | Description
------------- | -------------
-No Data | Set alert rule state to `NoData`
-Alerting | Set alert rule state to `Alerting`
-Keep Last State | Keep the current alert rule state, what ever it is.
-Ok | Not sure why you would want to send yourself an alert when things are okay, but you could.
+| No Data Option  | Description                                                                                |
+| --------------- | ------------------------------------------------------------------------------------------ |
+| No Data         | Set alert rule state to `NoData`                                                           |
+| Alerting        | Set alert rule state to `Alerting`                                                         |
+| Keep Last State | Keep the current alert rule state, what ever it is.                                        |
+| Ok              | Not sure why you would want to send yourself an alert when things are okay, but you could. |
 
 ### Execution errors or timeouts
 
 Tell Grafana how to handle execution or timeout errors.
 
-Error or timeout option | Description
------------- | -------------
-Alerting | Set alert rule state to `Alerting`
-Keep Last State | Keep the current alert rule state, what ever it is.
+| Error or timeout option | Description                                         |
+| ----------------------- | --------------------------------------------------- |
+| Alerting                | Set alert rule state to `Alerting`                  |
+| Keep Last State         | Keep the current alert rule state, what ever it is. |
 
 If you have an unreliable time series store from which queries sometime timeout or fail randomly you can set this option to `Keep Last State` in order to basically ignore them.
 
@@ -121,7 +121,7 @@ The actual notifications are configured and shared between multiple alerts. Read
 [Alert notifications]({{< relref "notifications.md" >}}) for information on how to configure and set up notifications.
 
 - **Send to -** Select an alert notification channel if you have one set up.
-- **Message -** Enter a message to be sent on the notification channel. The message can be in text, markdown, or HTML format. It can include links and variables as well.
+- **Message -** Enter a text message to be sent on the notification channel. Some alert notifiers support transforming the text to HTML or other rich formats.
 - **Tags -** Specify a list of tags (key/value) to be included in the notification. It is only supported by [some notifiers]({{< relref "notifications/#all-supported-notifiers" >}}).
 
 ## Alert state history and annotations