add pull_request_template.md

Author: nick1udwig

pull_request_template.md

@@ -0,0 +1,15 @@
+## Problem
+
+{A brief description of the problem, along with necessary context.}
+
+## Solution
+
+{A brief description of how you solved the problem.}
+
+## Docs Update
+
+[Corresponding docs PR](https://github.com/kinode-dao/kinode-book/pull/my-pr-number)
+
+## Notes
+
+{Any other information useful for reviewers.}