Improve bug report template.

Suggest looking at changelog in case of regressions.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,20 +7,29 @@ assignees: ''
 
 ---
 <!--
-Thank you for reporting an issue! Before you continue, please make sure that you have
+Thank you for reporting an issue!
+Before you continue, please make sure that you have
 
-- searched the [issue tracker](https://github.com/jgm/pandoc/issues) for similar issues (including closed issues).
-- searched the [discussion forum](https://github.com/jgm/pandoc/discussions) for
-  solutions.
-- reproduced your issue on the [latest release of pandoc](https://github.com/jgm/pandoc/releases), or online at [try pandoc](https://pandoc.org/try).
+- reproduced your issue with the latest release of pandoc
+  (https://github.com/jgm/pandoc/releases), or online (https://pandoc.org/try).
+- searched the issue tracker (https://github.com/jgm/pandoc/issues)
+  for similar issues (including closed issues).
+- searched the discussion forum
+  (https://github.com/jgm/pandoc/discussions) for solutions.
+
+If you are experiencing a regression (an unwanted change of
+behavior from an earlier version of pandoc), please indicate
+this and give relevant version numbers. Be sure to check the
+release notes (https://pandoc.org/releases) for relevant
+changes, as you might find a solution there.
 
 Note that this bug tracker is for reporting bugs, not asking
-questions.  For questions, use the [discussion
-forum](https://github.com/jgm/pandoc/discussions).
+questions. For questions, use the discussion forum:
+https://github.com/jgm/pandoc/discussions.
 -->
 
 **Explain the problem.**
 Include the **exact command line** you used and **all inputs necessary to reproduce the issue**.  Please create as minimal an example as possible, to help the maintainers isolate the problem.  Explain the output you received and how it differs from what you expected.
 
 **Pandoc version?**
-What version of pandoc are you using, on what OS? (If it's not the latest release, please try with the latest release before reporting the issue.)
+What version of pandoc are you using, on what OS? (If it's not the latest release, please try with the latest release before reporting the issue. Note that many linux distributions have old versions of pandoc in their repositories.)