chore: fix typo (#800)

Author: Rich-Harris

documentation/docs/30-add-ons/17-mcp.md

@@ -12,7 +12,7 @@ npx sv add mcp
 
 ## What you get
 
-- A MCP configuration for [local](https://svelte.dev/docs/mcp/local-setup) or [remote](https://svelte.dev/docs/mcp/remote-setup) setup
+- An MCP configuration for [local](https://svelte.dev/docs/mcp/local-setup) or [remote](https://svelte.dev/docs/mcp/remote-setup) setup
 - A [README for agents](https://agents.md/) to help you use the MCP server effectively
 
 ## Options