Update actions.md with iteration ckarification (#5521)

Clearer language for accessing the `iteration` parameter for the repeat action. Also update example to demonstrate how to use iteration.

Author: Aperion

content/automations/actions.md

@@ -253,16 +253,18 @@ on_...:
   - repeat:
       count: 5
       then:
+        - lambda: ESP_LOGI("main", "Turning lights on for iteration [%d]", iteration);
         - light.turn_on: some_light
         - delay: 1s
+        - lambda: ESP_LOGI("main", "Turning lights off for iteration [%d]", iteration);
         - light.turn_off: some_light
         - delay: 10s
 ```
 
 #### Configuration variables
 
 - **count** (**Required**, int): The number of times the action should be repeated. The counter is available to
-  lambdas using the reserved word "iteration".
+  lambdas using the implicit script parameter `iteration`.
 
 - **then** (**Required**, [Action](#config-action)): The action to repeat.