Add link to bugcrowd in issue template (#2716)

Author: leto

.github/ISSUE_TEMPLATE.md

@@ -4,7 +4,7 @@ This issue tracker is only for technical issues related to Dash Core.
 
 General Dash questions and/or support requests and are best directed to the [Dashpay Reddit](https://www.reddit.com/r/dashpay/).
 
-To report critical security issues, email infosec@dash.org instead of creating Github issues.
+To report critical security issues, email infosec@dash.org and/or see the DASH bug bounty program on [Bugcrowd](https://bugcrowd.com/dashdigitalcash) instead of creating Github issues.
 
 ### Describe the issue