Fix maxlength attribute for forms

Author: michaelperrin

forms.rst

@@ -568,10 +568,10 @@ the correct values of a number of field options.
     field ``nullable``). This is very useful, as your client-side validation will
     automatically match your validation rules.
 
-``max_length``
-    If the field is some sort of text field, then the ``max_length`` option can be
-    guessed from the validation constraints (if ``Length`` or ``Range`` is used) or
-    from the Doctrine metadata (via the field's length).
+``maxlength``
+    If the field is some sort of text field, then the ``maxlength`` option attribute
+    can be guessed from the validation constraints (if ``Length`` or ``Range`` is used)
+    or from the Doctrine metadata (via the field's length).
 
 .. caution::