Add a "why" to feature request

Author: styfle

.github/ISSUE_TEMPLATE/Feature_request.md

@@ -4,11 +4,11 @@ about: Marked doesn't do this thing and I think it should
 
 ---
 
-**Is your feature request related to a problem? Please describe.**
-A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+**Describe the feature**
+A clear and concise description of what you would like.
 
-**Describe the solution you'd like**
-A clear and concise description of what you want to happen.
+**Why is this feature necessary?**
+A clear and concise description of why.
 
 **Describe alternatives you've considered**
 A clear and concise description of any alternative solutions or features you've considered.