chore: add commitizen config

Author: cwillisf

README.md

@@ -68,3 +68,20 @@ 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

@@ -63,5 +63,10 @@
     "scratch-storage": "^1.0.0",
     "scratch-svg-renderer": "0.2.0",
     "twgl.js": "4.4.0"
+  },
+  "config": {
+    "commitizen": {
+      "path": "cz-conventional-changelog"
+    }
   }
 }