Remove community health files

Author: sagikazarmark

.github/CONTRIBUTING.md

@@ -43,18 +43,10 @@ $ composer test
 ```
 
 
-## Contributing
-
-Please see our [contributing guide](http://docs.php-http.org/en/latest/development/contributing.html).
-
 ## Credits
 
 Thanks to [Cuzzle](https://github.com/namshi/cuzzle) for inpiration for the `CurlCommandFormatter`.
 
-## Security
-
-If you discover any security related issues, please contact us at [[email protected]](mailto:[email protected]).
-
 
 ## License