Gitea: add more complete pull request template

.gitea/pull_request_template.md

@@ -1,4 +0,0 @@
----
-name: Pull Request
-about: Submit a pull request
----

.gitea/pull_request_template.yaml

@@ -0,0 +1,19 @@
+name: Pull Request
+about: Contribute code to Blender
+ref: master
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Guides to [Contributing Code](https://wiki.blender.org/index.php/Dev:Doc/Process/Contributing_Code) and effective [Code Review](https://wiki.blender.org/index.php/Dev:Doc/Tools/Code_Review).
+
+        By submitting code here, **you agree that the code is (compatible with) GNU GPL v2 or later**.
+
+  - type: textarea
+    id: body
+    attributes:
+      label: "Description"
+      value: |
+               Description of the problem that is addressed in the patch.
+
+               Description of the proposed solution and its implementation.