Add AppImage binary instructions

Author: Clue88

README.md

@@ -33,3 +33,50 @@ To add screenshots:
 * Screenshots must be generally 16x9 and no larger than 1600px by 900px.
 * Add the screenshot to `org.sugarlabs.MusicBlocks.appdata.xml`.
 * Screenshots should follow [AppStream specifications](https://www.freedesktop.org/software/appstream/docs/sect-Metadata-Application.html#tag-dapp-screenshots).
+
+### Creating AppImage Binaries
+1. Clone the [musicblocks-app](https://github.com/srevinsaju/musicblocks-app) GitHub repository and clone [musicblocks](https://github.com/sugarlabs/musicblocks.git) into the musicblocks-app directory.
+
+(The following are patch fixes that I'll create actual diff patches for – for now these are the changes)
+
+2. As of 2020-08-14, musicblocks-app has a bug that creates an infinite loop when closing the app. To fix this, comment out the following code in `main.js`:
+
+```
+ mainWindow.on('close', function(e){
+    var choice = require('electron').dialog.showMessageBoxSync(this,
+        {
+          type: 'question',
+          buttons: ['Yes', 'No'],
+          title: 'Confirm',
+          message: 'Are you sure you want to quit? You might have unsaved changes.'
+       });
+       if (choice == 1) {
+         e.preventDefault();
+       }
+  });
+  ```
+  
+  3. You'll also have to add the following line underneath `mainWindow.loadFile('musicblocks/index.html')`:
+  
+  ```
+  mainWindow.removeMenu()
+  ```
+  
+  4. Next, set `filename` to `defaultfilename` at line 87 in `musicblocks/js/SaveInterface.js` and comment out the `window.onbeforeunload` function at the end of the file.
+  
+  5. Enter the following commands into a command line window in the `musicblocks-app` directory:
+  
+  ```
+  $ npm install
+  $ npm install -g electron-builder
+  $ electron-builder build --linux --armv7l
+  $ electron-builder build --linux --arm64
+  $ electron-builder build --linux x64
+  ```
+  
+  6. Rename the create AppImage files (found in the `dist` folder) to:
+  * MusicBlocks-[version]-aarch64.AppImage (for --armv7l)
+  * MusicBlocks-[version]-arm.AppImage (for --arm64)
+  * MusicBlocks-[version]-x86_64.AppImage (for --x64)
+  
+  7. Create a release in this repository with the binaries attached.