Update implementations.md

Added "Oxygen JSON Editor" in the supported editors.
This support is available since 2018 (https://www.oxygenxml.com/xml_editor/whatisnew20.1.html#20.1JSON), and is continuously improved.

Author: octavianN

implementations.md

@@ -273,6 +273,7 @@ _None currently support draft-06 or later._
 
 _TODO: Sort by draft support._
 
+-   [Oxygen JSON Editor] (https://www.oxygenxml.com/xml_editor/json.html) -  JSON editor with a variety of editing features and helper views. Support for validation and editing JSON Schema draft-4, draft-6, and draft-7. Validation and editing of JSON files based on JSON Schema.
 -   [Altova XMLSpy 2019r3](https://www.altova.com/xmlspy-xml-editor#json_schema) - *Graphical JSON Schema editor for draft-06 and draft-7, as well as validation of JSON files based on JSON Schema*
 -   [Liquid XML Studio 2016](https://www.liquid-technologies.com/json-schema-editor) - *Graphical JSON schema editor for draft 4, context sensitive intellisense for JSON documents.*
 -   [Visual Studio 2013](https://www.visualstudio.com/) - *Auto-completion and tooltips based on JSON schema draft 3 and draft 4*