add vulnerability template

.github/ISSUE_TEMPLATE/vulnerability.md

@@ -0,0 +1,17 @@
+---
+name: Vulnerability
+about: Report a vulnerability in this extension.
+title: "[VUL] "
+labels: ''
+assignees: ''
+
+---
+
+**What is the vulnerability?**
+Describe the vulnerability in concise language.
+
+**Where is the vulnerability found?**
+Describe where the vulnerability is found.
+
+**What does this affect?**
+Explain what it affects. E.G: It opens up my school email to the world. etc.