Update README.md Documentation (#3151)

* Removed spacing so documentation link renders correctly

* Added link to security vulnerability process

* Updated process to policy and fixed broken link

Author: SkyeHoefling

README.md

@@ -24,8 +24,9 @@ In addition to robust content management, the free, open source DNN Platform inc
 
 ## Quick Links
 
-* [Documentation] (https://www.dnndocs.com/)
+* [Documentation](https://www.dnndocs.com/)
 * [Release Schedule](.github/RELEASE_SCHEDULE.md)
+* [Security Policy](SECURITY.md)
 * [DNN Digest](http://www.dnnsoftware.com/community/participate/subscribe-to-dnn-digest)
 * [Discussion Forums](https://dnncommunity.org/forums)
 * [Community Showcase](https://dnncommunity.org/Showcase)