Doc: update feature request issue template to use yml format

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,19 @@
+name: Feature request
+description: Suggest a feature to add to Gluetun
+title: "Feature request: "
+labels: [":bulb: feature request"]
+body:
+  - type: textarea
+    id: description
+    attributes:
+      label: "What's the feature 🧐"
+      placeholder: "Make the tunnel resistant to earth quakes"
+    validations:
+      required: true
+  - type: textarea
+    id: extra
+    attributes:
+      label: "Extra information and references"
+      placeholder: |
+        - I tried `docker run something` and it doesn't work
+        - That [url](https://github.com/qdm12/gluetun) is interesting