docs: add Factory CLI configuration to MCP clients (#523)

This PR adds Factory CLI to the MCP client configuration section in the
README.

The Factory CLI section:
- Follows the same format as other MCP clients
- Is placed in alphabetical order (between Cursor and Gemini CLI)
- Includes a link to the Factory documentation
- Provides the command to add the Chrome DevTools MCP server using
`droid mcp add`

Author: enoreyes

README.md

@@ -152,6 +152,16 @@ Go to `Cursor Settings` -> `MCP` -> `New MCP Server`. Use the config provided ab
 
 </details>
 
+<details>
+  <summary>Factory CLI</summary>
+Use the Factory CLI to add the Chrome DevTools MCP server (<a href="https://docs.factory.ai/cli/configuration/mcp">guide</a>):
+
+```bash
+droid mcp add chrome-devtools "npx -y chrome-devtools-mcp@latest"
+```
+
+</details>
+
 <details>
   <summary>Gemini CLI</summary>
 Install the Chrome DevTools MCP server using the Gemini CLI.