Update CONTRIBUTING.md

Matt A · web-flow · commit 3ef5eea9cedd · 2018-02-10T13:48:36.000-05:00
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -4,6 +4,7 @@ Contributions are **welcome** and will be fully **credited**.
 
 We accept contributions via Pull Requests on [Github](https://github.com/thephpleague/json-guard).
 
+If you plan to implement a new feature please open an issue first.  The core library aims to fully support the JSON Schema standard.  Features that are not part of the JSON Schema specification are unlikely to be merged.
 
 ## Pull Requests
 

Original file line number	Diff line number	Diff line change
`@@ -4,6 +4,7 @@ Contributions are welcome and will be fully credited.`
`4`	`4`
`5`	`5`	`We accept contributions via Pull Requests on [Github](https://github.com/thephpleague/json-guard).`
`6`	`6`
	`7`	`+If you plan to implement a new feature please open an issue first. The core library aims to fully support the JSON Schema standard. Features that are not part of the JSON Schema specification are unlikely to be merged.`
`7`	`8`
`8`	`9`	`## Pull Requests`
`9`	`10`