Update ISSUE_TEMPLATE.md

Update phrasing.

Author: Francesco Schwarz

.github/ISSUE_TEMPLATE.md

@@ -12,36 +12,36 @@ If you want your bug report
 use this issue template. Thank you.
 -->
 
-### Briefly describe the issue.
+### Short description of the issue
 
 Short description goes here.
 
-### What did you expect to happen?
+### Expected behavior
 
 Expected behavior goes here.
 
-### What did actually happen?
+### Actual behavior
 
 Actual behavior goes here.
 
-### Optional: Do you have screenshots/links that demonstrate the issue?
+### Optional: Screenshots/Links that demonstrate the issue
 
 Your screenshots/links go here.
 
-### Optional: Have you a suggestion for a possible fix?
+### Optional: Suggestion for a possible fix
 
 Your possible fix goes here.
 
-### What are the steps to reproduce the issue?
+### Steps to reproduce the issue
 <!-- Provide an unambiguous set of steps to reproduce the issue. -->
 
 1. Step 1
 2. Step 2
 3. Step 3
 
-### Tell us about the setup you experienced the bug in.
+### Setup/Environment
 <!--
-* Include as many relevant details about your environment setup.
+* Include as many relevant details about your environment setup as possible.
 * Hint: Using the Tracy Debugger module makes this a breeze: https://processwire.com/blog/posts/introducing-tracy-debugger/#versions-list
 -->