Add action comments to README.md (#1082)

README.md

@@ -350,6 +350,16 @@ error reporting for the entire file.
 For targeted exclusions across entire files (e.g., "Ignore all F841 violations in
 `/path/to/file.py`"), see the [`per-file-ignores`](#per-file-ignores) configuration setting.
 
+### "Action Comments"
+
+Ruff respects `isort`'s ["Action Comments"](https://pycqa.github.io/isort/docs/configuration/action_comments.html)
+(`# isort: skip_file`, `# isort: on`, `# isort: off`, `# isort: skip`, and `isort: split`), which
+enable selectively enabling and disabling import sorting for blocks of code and other inline
+configuration.
+
+See the [`isort` documentation](https://pycqa.github.io/isort/docs/configuration/action_comments.html)
+for more.
+
 ### Automating `noqa` Directives
 
 Ruff supports several workflows to aid in `noqa` management.