updated README.md

Author: cryi

README.md

@@ -31,6 +31,7 @@ Library exports json.lua like and JS like api.
       - `indent` - default `"    "`. Accepts string of whitespace characters or a number representing number of spaces (non indented HJSON is JSON, automatically forwards to `_to_json` version)
       - `skipkeys` - default `true`  Skips invalid keys. If false throws error on invalid key.
         - Valid key types: `boolean`, `nil`, `string`
+      - `sortKeys` - whether to sort keys in objects
       - `item_sort_key` - sort function which is passed to `table.sort` sorting object keys 
       - `invalidObjectsAsType` if true functions and others objects are replaced with their type name in format `__lua_<type>` e.g. `__lua_function`
 - Lua object to JSON - returns JSON string
@@ -42,6 +43,7 @@ Library exports json.lua like and JS like api.
       - `indent` - default `"    "`. Accepts string of whitespace characters or a number representing number of spaces (non indented HJSON is JSON, automatically forwards to `_to_json` version)
       - `skipkeys` - default `true`  Skips invalid keys. If false throws error on invalid key.
         - Valid key types: `boolean`, `nil`, `string`
+      - `sortKeys` - whether to sort keys in objects
       - `item_sort_key` - sort function which is passed to `table.sort` sorting object keys 
       - `invalidObjectsAsType` if true functions and others objects are replaced with their type name in format `__lua_<type>` e.g. `__lua_function`
 - H/JSON to Lua object - returns Lua object