Document `--indent` for pretty-format-json
diff --git a/README.md b/README.md
index 6c3a3ec..ee77b25 100644
--- a/README.md
+++ b/README.md
@@ -52,8 +52,9 @@
     - Use `args: ['--django']` to match `test*.py` instead.
 - `pyflakes` - Run pyflakes on your python files.
 - `pretty-format-json` - Checks that all your JSON files are pretty
-    - Use `args: ['--autofix']` to automatically fixing the encountered not-pretty-formatted files and
-    `args: ['--no-sort-keys']` to disable the sort on the keys.
+    - `--autofix` - automatically format json files
+    - `--no-sort-keys` - when autofixing, retain the original key ordering (instead of sorting the keys)
+    - `--indent ...` - Control the indentation (either a number for a number of spaces or a string of whitespace).
 - `requirements-txt-fixer` - Sorts entries in requirements.txt
 - `trailing-whitespace` - Trims trailing whitespace.
     - Markdown linebreak trailing spaces preserved for `.md` and`.markdown`;