Updates contributing docs

Author: Nikhil-Vats

CONTRIBUTING.md

@@ -50,6 +50,71 @@ yo biojs-webcomponents
 
 Note: If you have installed the generator-biojs-webcomponents globally, there is no need to worry, this method will still work. You do not need to uninstall anything.
 
+### About the project
+
+The project directory has the following structure -
+
+```bash
+├── __tests__
+│   └────── app.js
+├── .github
+│   └────── issue_template.md
+│   └────── pull_request_template.md
+├── generators
+│   └────── app
+│           └────── templates
+|           |       ├── dev
+|           |       │   └────── serve.js
+|           |       ├── examples
+|           |       │   └────── index.html
+|           |       ├── img
+|           |       │   └────── favicon.png
+|           |       ├── node_modules
+|           |       │   ├────── modules
+|           |       ├── src
+|           |       │   ├────── index.js
+|           |       │   └────── style.less
+|           |       ├── index.html
+|           |       ├── LICENSE
+|           |       ├── package.json
+|           |       ├── package-lock.json
+|           |       ├── README.md
+|           |       └── webpack.config.js
+|           |
+│           └────── index.js
+│           └────── validator.js
+├── node_modules
+│   ├────── modules
+├── .editorconfig
+├── .eslintignore
+├── .gitattributes
+├── .gitignore
+├── .travis.yml
+├── .yo-rc.json
+├── .CONTRIBUTING.md
+├── LICENSE
+├── package-lock.json
+├── package.json
+└── README.md
+```
+
+#### __tests__
+Contains the test file - app.js which has all the tests for the generator.
+
+#### .github
+Contains templates for GitHub issues and pull requests, make sure to follow these when you submit an issue/PR.
+
+#### generators
+Contains all the code for generator.
+
+1. app/templates - Contains all the templates which are generated whenever any user runs the generator. Read the directory structure and the purpose of each folder inside the templates folder [here](README.md##ii-description-of-your-projects-folder-structure).
+
+2. app/index.js - Contains all the initializing code, prompts, writing code which actually uses the [templates](generators/app/templates) to generate the web-component project and installs required dependencies. 
+
+3. app/validator.js - Contains the validator functions for the prompts which checks user inputs and also performs other functions like copying the build file, installing the component as npm package, downloading the build file from npm package and validating npm package's version.
+
+All the other files are self explanatory.
+
 ### To-do / roadmap. 
 
 See [issues](issues) for more details - we still need the following: