docs: mention Node.js pre-requisite in MCP docs (adobe#9474)

Author: reidbarber

packages/dev/s2-docs/pages/react-aria/mcp.mdx

@@ -12,6 +12,10 @@ export const tags = ['mcp', 'ai', 'documentation', 'tools'];
 
 <PageDescription>Learn how to use the React Aria [MCP](https://modelcontextprotocol.io/docs/getting-started/intro) server to help AI agents browse the documentation.</PageDescription>
 
+## Pre-requisites
+
+[Node.js](https://nodejs.org/) must be installed on your system to run the MCP server.
+
 ## Using with an MCP client
 
 Add the server to your MCP client configuration (the exact file and schema may depend on your client).

packages/dev/s2-docs/pages/s2/mcp.mdx

@@ -12,6 +12,10 @@ export const tags = ['mcp', 'ai', 'documentation', 'tools'];
 
 <PageDescription>Learn how to use the React Spectrum [MCP](https://modelcontextprotocol.io/docs/getting-started/intro) server to help AI agents browse the documentation.</PageDescription>
 
+## Pre-requisites
+
+[Node.js](https://nodejs.org/) must be installed on your system to run the MCP server.
+
 ## Using with an MCP client
 
 Add the server to your MCP client configuration (the exact file and schema may depend on your client).