chore: add commitizen config

Author: cwillisf

README.md

@@ -28,3 +28,20 @@ npm test
 
 ## Donate
 We provide [Scratch](https://scratch.mit.edu) free of charge, and want to keep it that way! Please consider making a [donation](https://secure.donationpay.org/scratchfoundation/) to support our continued engineering, design, community, and resource development efforts. Donations of any size are appreciated. Thank you!
+
+## Committing
+
+This project uses [semantic release](https://github.com/semantic-release/semantic-release) to ensure version bumps
+follow semver so that projects depending on it don't break unexpectedly.
+
+In order to automatically determine version updates, semantic release expects commit messages to follow the
+[conventional-changelog](https://github.com/bcoe/conventional-changelog-standard/blob/master/convention.md)
+specification.
+
+You can use the [commitizen CLI](https://github.com/commitizen/cz-cli) to make commits formatted in this way:
+
+```bash
+npm install -g commitizen@latest cz-conventional-changelog@latest
+```
+
+Now you're ready to make commits using `git cz`.

package.json

@@ -42,5 +42,10 @@
     "web-audio-test-api": "0.5.2",
     "webpack": "4.46.0",
     "webpack-cli": "3.3.12"
+  },
+  "config": {
+    "commitizen": {
+      "path": "cz-conventional-changelog"
+    }
   }
 }