Minor syntax changes.

You are validating the data, not users.

Fixes #5587: `json_encode` is now used with `JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE` where it makes sense, also it is now default for `Json::encode()`

In line 180. 
It should be .val() instead of .value.

This is my first edit.

fixes #2268

Updated guide

fixes #4482

Fixed typo in validation guide

Note: should confirm that my additions of “inclusive” is correct.