Create PULL_REQUEST_TEMPLATE.md

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,25 @@
+**Type of PR:**
+- [ ] Bugfix
+- [ ] Feature
+- [ ] Documentation
+- [ ] Other
+
+**Required reviews:** 
+- [ ] 1
+- [ ] 2
+- [X] 3
+
+**What this does:**
+> High-level idea of the changes introduced in this PR. 
+> List relevant API changes (if any), as well as related PRs and issues.
+
+**Issues fixed/closed:**
+> - Fixes #...
+
+**Why it's needed:**
+> Explain how this PR fits in the greater context of the NuCypher Network.
+> E.g., if this PR addresses a `nucypher/productdev` issue, let reviewers know!
+
+**Notes for reviewers:**
+> What should reviewers focus on? 
+> Is there a particular commit/function/section of your PR that requires more attention from reviewers?