Fix a Typo (#74)

Author: redcinelli

docs/intro.asciidoc

@@ -183,7 +183,7 @@ Refer to the documentation of the individual loggers on how to set these fields.
 |ECS field | Description | Example
 
 |{ecs-ref}/ecs-service.html[`service.name`]
-| Helps to filer the logs by service.
+| Helps to filter the logs by service.
 |`"my-service"`
 
 |{ecs-ref}/ecs-event.html[`event.dataset`]