Add introductory text for FRs and bug reports

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -4,6 +4,12 @@ about: Report a reproducible bug in the current release of NetBox
 labels: ["type: bug"]
 issue_body: false
 body:
+  - type: markdown
+  attributes:
+    value: "**NOTE:** This form is only for reporting _reproducible bugs_ in a
+    current NetBox installation. If you're having trouble with installation or just
+    looking for assistance with using NetBox, please visit our
+    [discussion forum](https://github.com/netbox-community/netbox/discussions) instead."
   - type: input
     attributes:
       label: NetBox version

.github/ISSUE_TEMPLATE/feature_request.yaml

@@ -4,6 +4,12 @@ about: Propose a new NetBox feature or enhancement
 labels: ["type: feature"]
 issue_body: false
 body:
+  - type: markdown
+  attributes:
+    value: "**NOTE:** This form is only for submitting well-formed proposals to extend or
+    modify NetBox in some way. If you're trying to solve a problem but can't figure out how,
+    or if you still need time to work on the details of a proposed new feature, please start
+    a [discussion](https://github.com/netbox-community/netbox/discussions) instead."
   - type: input
     attributes:
       label: NetBox version