chore: add Gitpod (#238)

* chore: add Gitpod

* docs: add single-click setup with Gitpod

Co-authored-by: louistiti <louis.grenard@gmail.com>

.github/CONTRIBUTING.md

@@ -25,16 +25,19 @@ Here are few examples about how you could help on Leon, by:
 **Working on your first Pull Request?** You can learn how from this *free* series [How to Contribute to an Open Source Project on GitHub](https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github).
 
 - **Please first discuss** the change you wish to make via [issue](https://github.com/leon-ai/leon/issues),
-email, or any other method with the owners of this repository before making a change.
-It might avoid a waste of your time.
+  email, or any other method with the owners of this repository before making a change.
+  It might avoid a waste of your time.
+
 - The `master` branch is actually used as a snapshot of the latest stable release. **Do not submit your PRs
-against the `master` branch**.
+  against the `master` branch**.
+
 - Ensure your code **respect our coding standards** (cf. [.eslintrc.json](https://github.com/leon-ai/leon/blob/develop/.eslintrc.json)).
 To do so, you can run:
 
   ```sh
   npm run lint
   ```
+  
 - Make sure your **code passes the tests**. You can run the tests via the following command:
   
   ```sh
@@ -42,9 +45,19 @@ To do so, you can run:
   ```
   
   If you're adding new features to Leon, please include tests.
-  
+
 ## Development Setup
 
+Choose the setup method you want to go for.
+
+### Single-Click
+
+Gitpod will automatically setup an environment and run an instance for you.
+
+[![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/#https://github.com/leon-ai/leon)
+
+### Basic
+
 ```sh
 # Clone the repository
 git clone https://github.com/leon-ai/leon.git leon
@@ -65,7 +78,7 @@ npm run dev:server
 npm run dev:app
 ```
 
-## Development Setup with Docker
+### Docker
 
 ```sh
 # Clone the repository

.gitpod.yml

@@ -0,0 +1,19 @@
+image: 'gitpod/workspace-full'
+
+tasks:
+  - before: 'npm install'
+    init: 'npm run check && npm run build'
+    command: 'npm start'
+
+ports:
+  - port: 1337
+    onOpen: 'notify'
+
+github:
+  prebuilds:
+    master: true
+    branches: true
+    pullRequests: true
+    addComment: true
+    addBadge: true
+    addLabel: true

README.md

@@ -65,6 +65,12 @@ If you want to, Leon can communicate with you by being **offline to protect your
 
 Sounds good for you? Then let's get started!
 
+## ☁️ Try with a Single-Click
+
+Gitpod will automatically setup an environment and run an instance for you.
+
+[![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/#https://github.com/leon-ai/leon)
+
 ## 🚀 Getting Started
 
 ### Prerequisites