Merge pull request rails#42347 from HParker/mention-executable-test-case-in-issue-template

Author: zzak

.github/issue_template.md

@@ -2,6 +2,11 @@
 <!-- (Guidelines for creating a bug report are [available
 here](https://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#creating-a-bug-report)) -->
 
+<!-- Paste your executable test case created from one of the scripts found [here](https://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#create-an-executable-test-case) below: -->
+```ruby
+# Your reproduction script goes here
+```
+
 ### Expected behavior
 <!-- Tell us what should happen -->