fix(content): correct example in suggested_output example

Co-authored-by: Federico Di Pierro <nierro92@gmail.com>
Signed-off-by: Leonardo Grasso <me@leonardograsso.com>

content/en/docs/concepts/outputs/formatting.md

@@ -69,7 +69,7 @@ append_output:
   - suggested_output: true  # Enable the use of extractor plugins' suggested fields for all matching sources.
 ```
 
-When `suggested_output` is set to `true`, any extractor plugin that provides "suggested" fields will add them to the output in the form `plugin_field_name=$plugin.field`.
+When `suggested_output` is set to `true`, any extractor plugin that provides "suggested" fields will add them to the output in the form `plugin_field_name=$plugin.field_name`.
 
 ### Command-Line Usage