Fix typo

wooorm · wooorm · commit 102c75e2801e · 2020-09-09T20:29:08.000+02:00
diff --git a/readme.md b/readme.md
@@ -63,7 +63,7 @@ would otherwise turn into a list and image respectively):
 
 ## API
 
-### `toMarkdown(doc[, options])`
+### `toMarkdown(tree[, options])`
 
 Serialize **[mdast][]** to markdown.
 
