Create issue template for feature request (#321)

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,21 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: Feature request
+label: backlog
+---
+
+## Suggestion
+
+<!-- A summary of what you'd like to see added or changed -->
+
+## Use Cases
+
+<!--
+What do you want to use this for?
+What shortcomings exist with current approaches?
+-->
+
+## Examples
+
+<!-- Show how this would be used and what the behavior would be -->