minor changes to headlines structure

Author: MeelahMe

content/shared/influxdb3-cli/test/schedule_plugin.md

@@ -44,7 +44,7 @@ In the examples below, replace the following:
 
 {{% code-placeholders "DATABASE_NAME|AUTH_TOKEN|PLUGIN_FILENAME" %}}
 
-## Test a schedule plugin
+### Test a schedule plugin
 
 <!--pytest.mark.skip-->
 
@@ -54,4 +54,5 @@ influxdb3 test schedule_plugin \
   --token AUTH_TOKEN \
   PLUGIN_FILENAME.py
 ```
-{{% /code-placeholders %}}
+{{% /code-placeholders %}}
+