Update readme for draft 7 (#899)

## Description

Updates the Readme.md to include info about the Draft-7 support

## Related Issue

N/A

## Type of Change

<!-- Mark the appropriate option with an "x" -->

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [X] Documentation update
- [ ] Code refactoring
- [ ] Other (please describe):

## Checklist

<!-- Mark completed items with an "x" -->

- [X] I have read the [CONTRIBUTING](CONTRIBUTING.md) guidelines
- [X] My code follows the code style of this project
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] All new and existing tests pass
- [X] I have updated the documentation accordingly
- [X] My changes generate no new warnings

## Additional Notes

<!-- Add any additional information that might be helpful for reviewers
-->

Author: DannyvdSluijs

README.md

@@ -6,7 +6,7 @@
 ![Supported Dialects](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fphp-justinrainbow-json-schema%2Fsupported_versions.json)
 
 A PHP Implementation for validating `JSON` Structures against a given `Schema` with support for `Schemas` of Draft-3,
-Draft-4 or Draft-6.
+Draft-4, Draft-6 or Draft-7.
 
 Features of newer Drafts might not be supported. See [Table of All Versions of Everything](https://json-schema.org/specification-links.html#table-of-all-versions-of-everything) to get an overview
 of all existing Drafts. See [json-schema](http://json-schema.org/) for more details about the JSON Schema specification
@@ -15,6 +15,7 @@ of all existing Drafts. See [json-schema](http://json-schema.org/) for more deta
 ![Draft 3](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fphp-justinrainbow-json-schema%2Fcompliance%2Fdraft3.json)
 ![Draft 4](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fphp-justinrainbow-json-schema%2Fcompliance%2Fdraft4.json)
 ![Draft 6](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fphp-justinrainbow-json-schema%2Fcompliance%2Fdraft6.json)
+![Draft 7](https://img.shields.io/endpoint?url=https%3A%2F%2Fbowtie.report%2Fbadges%2Fphp-justinrainbow-json-schema%2Fcompliance%2Fdraft7.json)
 
 
 ## Installation
@@ -37,17 +38,17 @@ composer require justinrainbow/json-schema
 
 For a complete reference see [Understanding JSON Schema](https://json-schema.org/understanding-json-schema/).
 
-__Note:__ features of Drafts newer than Draft-4 might not be supported!
+__Note:__ Not all drafts might be supported, check the [Bowtie report](https://bowtie.report/#/implementations/php-justinrainbow-json-schema) on the current state of draft implementations.
 
 ### Basic usage
 
 ```php
 <?php
 
-$data = json_decode(file_get_contents('data.json'));
+$data = json_decode(file_get_contents('data.json'), false);
 
 // Validate
-$validator = new JsonSchema\Validator;
+$validator = new JsonSchema\Validator();
 $validator->validate($data, (object)['$ref' => 'file://' . realpath('schema.json')]);
 
 if ($validator->isValid()) {
@@ -231,4 +232,4 @@ Thanks go to these wonderful people, without their effort this project wasn't po
 
 <a href="https://github.com/jsonrainbow/json-schema/graphs/contributors">
   <img src="https://contrib.rocks/image?repo=jsonrainbow/json-schema" />
-</a>
+</a>