Add Dockerfile & local running instructions

Dockerfile

@@ -0,0 +1,7 @@
+FROM node:lts
+WORKDIR /app
+COPY package.json yarn.lock ./
+RUN yarn install
+COPY . .
+RUN yarn build
+CMD ["yarn", "mm-snap", "serve"]

README.md

@@ -38,9 +38,70 @@ type State = {
 This snap exposes an `onRpcRequest` handler, which supports the following JSON-RPC methods:
 
 - `setState` - Set the state to the provided parameters. This assumes the new state is an object using the above structure. The state is always stored encrypted.
-- `getState` - Get the state from the snap. This returns the current state if one is set, or a default state otherwise. The method always retrieves state from the encrypted store.
-- `clearState` - Reset the state to the default state. The method always retrieves state from the encrypted store.
+- `getState` - Get the state from the snap. This returns the current state if one is set, or a default state otherwise. The state from the encrypted store is always retrieved.
+- `clearState` - Reset the state to the default state. The state from the encrypted store is always cleared.
 
-Interacting with encrypted storage requires MetaMask to be unlocked.
+Encrypted storage requires MetaMask to be unlocked.
 
 For more information, you can refer to [the end-to-end tests](./src/index.test.ts).
+
+## Running the Snap Locally
+
+### Prerequisites
+
+Make sure you have `nvm` (Node Version Manager) installed. If not, you can install it by following the instructions [here](https://github.com/nvm-sh/nvm#installing-and-updating).
+
+### Without Docker
+
+1. **Install the correct Node.js version:**
+
+   ```sh
+   nvm install
+   nvm use
+   ```
+
+   This will use the Node.js version specified in the `.nvmrc` file.
+
+2. **Install the dependencies:**
+
+   ```sh
+   yarn install
+   ```
+
+3. **Build the project:**
+
+   ```sh
+   yarn build
+   ```
+
+4. **Start the Snap:**
+
+   ```sh
+   yarn start
+   ```
+
+5. **Run tests:**
+
+   ```sh
+   yarn test
+   ```
+
+### With Docker
+
+You can also build and run this snap locally using Docker.
+
+1. **Build the Docker image**
+
+   Navigate to the directory containing the `Dockerfile` and run:
+
+   ```sh
+   docker build -t zazen-snap .
+   ```
+
+2. **Run the Docker container**
+
+   ```sh
+   docker run -d -p 8081:8081 zazen-snap
+   ```
+
+This command will run the container and map port `8081` of the container to port `8081` of your host machine, allowing you to access the snap locally for testing.