Update contributing

Author: ericglau

CONTRIBUTING.md

@@ -5,7 +5,9 @@ Contributions to OpenZeppelin Contracts Wizard are welcome. Please review the in
 
 ## Project layout
 
+- `packages/common` contains common code used internally by some of the below packages.
 - `packages/core` contains the code generation logic for each language under separately named subfolders.
+- `packages/mcp` contains the MCP server.
 - `packages/ui` is the interface built in Svelte.
 
 ## Building and testing the project
@@ -65,6 +67,29 @@ Then from the `packages/ui` directory:
 > [!TIP]
 > You can also start both the UI and API servers simultaneously by running `yarn dev` from the root directory.
 
+### Testing the MCP server (Optional)
+
+#### Running MCP tests
+From the `packages/mcp` directory:
+- ```yarn test```
+
+#### Running the local MCP server in your IDE
+1. From the `packages/mcp` directory, run `yarn watch` to compile and watch for changes.
+2. Configure your IDE's MCP configuration file with the following, replacing `<ABSOLUTE_PATH_TO_WIZARD_PROJECT_ROOT>` with the absolute path to the root directory of this repository:
+```
+{
+  "mcpServers": {
+    "openzeppelin-contracts-wizard": {
+      "command": "node",
+      "args": [
+        "<ABSOLUTE_PATH_TO_WIZARD_PROJECT_ROOT>/packages/mcp/dist/index.js"
+      ]
+    }
+  }
+}
+```
+3. When you make changes to the MCP server's code, refresh the MCP server in your IDE to pick up the changes.
+
 ## Creating Pull Requests (PRs)
 
 As a contributor, we ask that you fork this repository, work on your own fork and then submit pull requests. The pull requests will be reviewed and eventually merged into the main repo. See ["Fork-a-Repo"](https://help.github.com/articles/fork-a-repo/) for how this works.