Docs: add note to docs about zero-indexing for machine formatters (#4544

)

* Docs: add note to docs about zero-indexing for machine formatters

* Update index.md

docs/formatters/index.md

@@ -8,9 +8,12 @@ order: 2
 
 Lint _formatters_ allow for transformation of lint results into various forms before outputting to stdout or a file.
 
+Formatters are split into two categories: _human-readable_ and _machine-readable_. Please note that for machine-readable
+formatters formatters all positioning is zero-indexed (lines start with zero), whereas human-readable formatters are not (lines start with one).
+
 ### Built-in formatters
 
 {% assign formatters = site.data.formatters | sort: "name" %}
 {% for formatter in formatters %}
-* [{{formatter.formatterName}}]({{formatter.formatterName}}) - {{formatter.description | markdownify | remove:"<p>" | remove: "</p>"}}
-{% endfor %}
+* [{{formatter.formatterName}}]({{formatter.formatterName}}) - {{formatter.description | markdownify | remove:"<p>" | remove: "</p>"}} ({{formatter.consumer}}-readable)
+{% endfor %}