Fix confusing sentence

Closes GH-25.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

Author: capndave

readme.md

@@ -287,8 +287,8 @@ cli input.txt --setting 'golf: false, hotel-india: ["juliet", 1]'
 Configuration for the parser and compiler of the processor.
 Can be set from [configuration files][config-file].
 
-The given settings are [JSON5][], with one exceptions: surrounding braces must
-not be used: `"foo": 1, "bar": "baz"` is valid
+The given settings are [JSON5][], with one exception: surrounding braces must
+not be used.  Instead, use JSON syntax without braces, such as `"foo": 1, "bar": "baz"`.
 
 *   **Default**: none
 *   **Alias**: `-s`