Merge pull request OAI#1776 from tbarn/master

add Spectral to implementations

Author: Ron

IMPLEMENTATIONS.md

@@ -21,6 +21,8 @@ These tools are not endorsed by the OAI.
 | go-openapi | [github/nasa9084/go-openapi](https://github.com/nasa9084/go-openapi) | Go | Golang struct model for OpenAPI 3.x. |
 | openapi | [github/wzshiming/openapi](https://github.com/wzshiming/openapi) | Go | OpenAPI 3 Specification for golang |
 | kin-openapi | [github/getkin/kin-openapi](https://github.com/getkin/kin-openapi) | Go | OpenAPI 3.x implementation for Go (parsing, converting, validation) |
+| Spectral | [github/stoplightio/spectral](https://github.com/stoplightio/spectral) | TypeScript, JavaScript | A flexible JSON object linter with out of the box support for OpenAPI Specification 2 and 3 |
+
 
 #### Editors