Bug reporters are frequently not making the connection that "Steps to reproduce" means "steps for someone else to independently reproduce this bug", not "steps that I go through on my project to see this bug". Added some example text to gently steer people towards the level of detail we want...
Also trimmed down the "Wagtail version" item under "Technical details", since we don't really need to tell people four different ways to do the same thing. (We don't want people to mentally tune this text out, so I think it's a good habit to remove something for every new thing we add)
