[docs] document scripted-diff

doc/developer-notes.md

@@ -244,3 +244,24 @@ ACK -  A loose ACK can be confusing. It's best to avoid them unless it's a docum
 NACK - Disagree with the code changes/concept. Should be accompanied by an explanation.
 
 See the [Development Guidelines](https://zcash.readthedocs.io/en/latest/rtd_pages/development_guidelines.html) documentation for preferred workflows, information on continuous integration and release versioning.
+
+Scripted diffs
+--------------
+
+For reformatting and refactoring commits where the changes can be easily automated using a bash script, we use
+scripted-diff commits. The bash script is included in the commit message and our Travis CI job checks that
+the result of the script is identical to the commit. This aids reviewers since they can verify that the script
+does exactly what it's supposed to do. It is also helpful for rebasing (since the same script can just be re-run
+on the new master commit).
+
+To create a scripted-diff:
+
+- start the commit message with `scripted-diff:` (and then a description of the diff on the same line)
+- in the commit message include the bash script between lines containing just the following text:
+
+    - `-BEGIN VERIFY SCRIPT-`
+    - `-END VERIFY SCRIPT-`
+
+The scripted-diff is verified by the tool `contrib/devtools/commit-script-check.sh`
+
+Commit `bb81e173` is an example of a scripted-diff.