Ask issue openers to confirm that bugs are reproducible

.github/ISSUE_TEMPLATE.md

@@ -4,9 +4,8 @@ Found a bug? Please fill out the sections below. 👍
 
 A summary of the issue.
 
-### Steps to Reproduce
 
-It's essential that you provide enough information for someone else to replicate the problem you're seeing. Simply describing something that's broken on your current project is not enough!
+### Steps to Reproduce
 
 1. (for example) Start a new project with `wagtail start myproject`
 2. Edit models.py as follows...
@@ -14,6 +13,9 @@ It's essential that you provide enough information for someone else to replicate
 
 Any other relevant information. For example, why do you consider this a bug and what did you expect to happen instead?
 
+* I have confirmed that this issue can be reproduced as described on a fresh Wagtail project: (yes / no)
+
+
 ### Technical details
 
 * Python version: Run `python --version`.