Add security issue template and update issue prefixes

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,7 +1,7 @@
 ---
 name: Bug report
 about: Create a report to help us improve
-title: '[BUG]'
+title: '[BUG]: (please fill in...)'
 labels: ''
 assignees: ''
 

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,7 +1,7 @@
 ---
 name: Feature request
 about: Suggest an idea for McStas / McXtrace
-title: "[FEATURE]"
+title: "[FEATURE]: (please fill in...)"
 labels: ''
 assignees: ''
 

.github/ISSUE_TEMPLATE/security.md

@@ -0,0 +1,32 @@
+---
+name: Security concern
+about: Create a report to help us improve
+title: '[SECURITY]: (please fill in...)'
+labels: ''
+assignees: ''
+
+---
+
+**Describe your security concern**
+A clear and concise description of worry.
+
+**Document steps to reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**OS and McStas/McXtrace version (please complete the following information):**
+ - OS: [e.g. Linux]
+ - McCode variant [i.e. McStas, McXtrace]
+ - Version [e.g. 3.6.5]
+
+**Additional context**
+Add any other context about the problem here.