Update issue templates

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: feature
+assignees: ''
+
+---
+
+**Subsystem**
+Client/Server, particular relevant ktor module(s) if applicable.
+
+**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 solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Motivation to include to ktor**
+An explanation, why do you believe that the feature you'd like to see is important for other users as well and why it should be delivered with ktor.