add pr template

.github/pull_request_template.md

@@ -0,0 +1,21 @@
+## Pull Request Checklist
+
+Before you submit your pull request with a new example, please make sure you have completed the following tasks:
+
+- [ ] **Update Makefile:** Make sure the new example is included in the following Makefile commands:
+  - [ ] `install`
+  - [ ] `build`
+  - [ ] `test`
+  - [ ] `clean`
+
+- [ ] **Update opam file:** Ensure the new example is added to the list of dependencies in the `opam` file.
+
+- [ ] **Update README:** Add a link to the new example in the README. Provide a brief description if necessary.
+
+## Description
+
+Please replace this section to provide a brief description of the example you are creating with this pull request.
+
+## Additional Notes
+
+Add any additional information or notes here.