-`/src/index.ts`, which contains the entry point for the plugin source code.
-`/src/manifest.json`, which is the plugin manifest. It contains information such as the plugin a name, version, etc.
The plugin is built using webpack, which create the compiled code in `/dist`. The project is setup to use TypeScript, although you can change the configuration to use plain JavaScript.
To update the plugin framework, run `yo joplin --update`
Keep in mind that doing so will overwrite all the framework-related files **outside of the "src/" directory** (your source code will not be touched). So if you have modified any of the framework-related files, such as package.json or .gitignore, make sure your code is under version control so that you can check the diff and re-apply your changes.
For that reason, it's generally best not to change any of the framework files or to do so in a way that minimises the number of changes. For example, if you want to modify the Webpack config, create a new separate JavaScript file and include it in webpack.config.js. That way, when you update, you only have to restore the line that include your file.
