Update issue templates

.github/ISSUE_TEMPLATE/bug_report.md

@@ -11,6 +11,7 @@ assignees: ''
 **Note:**
 - Do not use the bug and feature tracker for support requests. Use the `cython-users` mailing list instead.
 - Did you search for similar issues already? Please do, it helps to save us precious time that we otherwise could not invest into development.
+- Did you try the latest master branch or pre-release? It might already have what you want to report.
 -->
 
 **Describe the bug**

.github/ISSUE_TEMPLATE/custom.md

+---
+name: Custom issue template
+about: General issue
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+<!--
+**Note:**
+- Do not use the bug and feature tracker for support requests. Use the `cython-users` mailing list instead.
+- Did you search for similar issues already? Please do, it helps to save us precious time that we otherwise could not invest into development.
+- Did you try the latest master branch or pre-release? It might already have what you want to report.
+-->
+
+```cython
+# descriptive code example
+```
+
+Cython version used: (e.g. 0.29.18)