docs: Add release intstructions to CONTRIBUTING

CONTRIBUTING.md

@@ -11,8 +11,10 @@ which uses
 Useful files (sample data, biomonitoring stations, icons)
 can be found on our Drive (Appsilon-internal; see bookmarks on the Slack channel)
 
-To be able to run inference,
-download the ONNX models and place them in the `assets/models` directory:
+## Models
+
+To run inference in development mode (`npm start`) or to build the installers (`npm run package`),
+you will need to download the ONNX models and place them in the `assets/models` directory:
 * [Central African forests (Gabon)](https://drive.google.com/uc?export=download&id=1HHmUdq5kUib2e05YgtBQGyS-146-Q5S5)
 * [East African savannas (Serengeti)](https://drive.google.com/uc?export=download&id=1UeJ4nIv_uORhmYqRGAKRjmcG39gTcBKn)
 * [East African savannas (Ol Pejeta Conservancy)](https://drive.google.com/uc?export=download&id=1YpRLde9t2OL-60a0M3vNeoem5tK6JjXJ)
@@ -31,6 +33,23 @@ You'll need [Node.js](https://nodejs.org/en/) 16 or later on your system.
 * `npm run package`: Package the app for the local platform.
 * `npx cross-env DEBUG_PROD=true npm run package`: Package the app with developer tools enabled.
 
+## Release instructions
+
+1. Choose a new version number according to [SemVer](https://semver.org/).
+2. Update the version in the repo:
+    1. Edit the `release/app/package.json` file.
+    2. Update `release/app/package-lock.json` by running `npm install` in the project root.
+    3. Make sure these changes are on the `main` branch before proceeding.
+3. [Create a new release](https://github.com/Appsilon/mbaza/releases/new) on GitHub.
+4. Build installers for the 3 operating systems:
+    1. Each one needs to be built on the target system.
+    2. Download the models and put them in the `assets/models` directory
+    (refer to the [Models](#models) section above).
+    3. Run `npm install` followed by `npm run package`.
+    4. The installer will be placed in the `release/build` directory.
+5. Sign the Windows installer using the code signing certificate stored in our 1Password.
+6. Upload the installers to the release.
+
 ## Definition of Done
 
 1. All changes are introduced in pull requests,