Web service API change related guidelines (#268)

.github/pull_request_template.md

@@ -10,8 +10,8 @@ Describe your changes here:
 ## Resolved issues
 
 <!--
-Note the Jira and GitHub issue(s) resolved by this PR (`Fixes|Resolves ...`).
-Make sure that the linked issue titles & descriptions are also up to date.
+- Note the Jira and GitHub issue(s) resolved by this PR (`Fixes|Resolves ...`).
+- Make sure that the linked issue titles & descriptions are also up to date.
 -->
 
 ## Documentation
@@ -24,9 +24,37 @@ Please make sure that...
 - Tests are included for the changed functionality in this PR. If to be merged without tests, please elaborate why.
 -->
 
+## Web service API changes
+
+<!--
+- Are there new endpoints introduced? Please detail for each of them...
+  - The rationale for introducing it
+  - The interface
+    - the HTTP verb
+    - the URL structure
+    - Versioning
+      - Is it expected to be long time stable? It should be versioned (e.g. `.../v2/...`)
+      - ... or it expected to evolve, perhaps expected to be a system internal need or something we are expecting to iterate on still? It should be marked unstable (e.g. `.../unstable/...`)
+    - the possible request body
+    - the response bodies and status code(s) for success and possible failure case(s)
+  - Authorization
+    - What credentials are required to access the resource?
+    - What automated test scenarios are included for authorization failures?
+- Are there changed database queries? (... which could cause performance regressions)
+- Are there required configuration changes?
+- Are there DB migrations included?
+- ... or other things you'd like to be aware of at deploy time?
+-->
+
 ## Tests
 
 <!--
 - How was this PR tested? Please provide steps to follow so that the reviewer(s) can test on their end.
 - Please provide a list of what tests were run.
 -->
+
+
+## Testing
+
+- How were these changes tested?
+- What should the reviewer do to test, if it's credibly locally testable? (Why is it not, if it isn't?)