Add GitHub Discussions category templates

Co-authored-by: blackboxprogramming <118287761+blackboxprogramming@users.noreply.github.com>

.github/DISCUSSION_TEMPLATE/ideas.yml

@@ -0,0 +1,23 @@
+title: "[Idea] "
+labels: []
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Share an idea for improving the repository, adding new content, or exploring new aspects of simulation theory.
+  - type: textarea
+    id: idea
+    attributes:
+      label: Idea Description
+      description: Describe your idea in detail.
+      placeholder: My idea is...
+    validations:
+      required: true
+  - type: textarea
+    id: motivation
+    attributes:
+      label: Motivation
+      description: Why do you think this would be valuable? What problem does it solve or what opportunity does it open?
+      placeholder: This would be valuable because...
+    validations:
+      required: false