github: Copy PULL_REQUEST_TEMPLATE.md from nuttx repo

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..f0c7312
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,6 @@
+## Summary
+
+## Impact
+
+## Testing
+