Add issue templates

Configured through https://github.com/zsh-users/zsh-autosuggestions/issues/templates/edit

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: enhancement
+assignees: ''
+
+---
+
+### 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. -->
+
+### Describe alternatives you've considered
+<!-- A clear and concise description of any alternative solutions or features you've considered. -->
+
+### Additional context
+<!-- Add any other context or screenshots about the feature request here. -->