Update issue templates

.github/ISSUE_TEMPLATE/unknown-issue-template.md

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+---
+name: unknown issue template
+about: Issue unknown
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+### Issue title
+
+### Issue Description
+
+### Versions:
+
+- Browser(s):
+- Nginx version:
+- Operating system of web server running Nginx:
+
+### Screenshot(s):
+
+[Screenshot(s) for difficult to describe visual issues are **mandatory**. Post links instead of **Inline Images** for Screenshots containing **Adult material**.]
+
+### Settings:
+
+- [List here all the changes you made to the default settings]
+
+### Other optional information you want to add other than the above: