Update PR template (#4318)

* Update PR template for regression testing

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,9 @@
 <!--
 Please open an [Issue](https://github.com/kong/insomnia/issues/new) first to discuss new
 features or non-trivial changes. Please provide as much detail as possible on the change as
-possible including general description, implementation details, potential shortcommings, etc.
+possible including general description, implementation details, potential shortcomings, etc.
 
 If this PR closes an issue, please mention "Closes #XX" where #XX is the issue number.
+
+If this PR fixes a bug or regression, please make sure to add a test.
 -->