Clarify that at least one fileset must be enabled in a filebeat module (

elastic#2053)

docs/en/observability/ingest-logs.asciidoc

@@ -92,7 +92,8 @@ include::{beats-repo-dir}/tab-widgets/enable-modules-widget.asciidoc[]
 --
 
 . In the module config under `modules.d`, change the module settings to match
-your environment.
+your environment. You must enable at least one fileset in the module.
+**Filesets are disabled by default.** 
 +
 For example, log locations are set based on the OS. If your logs aren't in
 default locations, set the `paths` variable:
@@ -102,6 +103,7 @@ default locations, set the `paths` variable:
 ----
 - module: nginx
   access:
+    enabled: true
     var.paths: ["/var/log/nginx/access.log*"] <1>
 ----
 --