diff --git a/CONTRIBUTING.asciidoc b/CONTRIBUTING.asciidoc
index 5f18e1546..abaa3b04c 100644
--- a/CONTRIBUTING.asciidoc
+++ b/CONTRIBUTING.asciidoc
@@ -446,11 +446,17 @@ flag an argument should get:
 [source,python]
 ----
 @cmdutils.register(...)
-@cmdutils.arg('bar', flag='c')
+@cmdutils.argument('bar', flag='c')
 def foo(bar):
     ...
 ----
 
+The following arguments are supported for `@cmdutils.argument`:
+
+- `flag`: Customize the short flag (`-x`) the argument will get.
+- `win_id=True`: Mark the argument as special window ID argument
+- `count=True`: Mark the argument as special count argument
+
 The name of an argument will always be the parameter name, with any trailing
 underscores stripped.